[Pcre-svn] [976] code/trunk: Add support for (?^) as now sup…

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Subject: [Pcre-svn] [976] code/trunk: Add support for (?^) as now supported by Perl.
Revision: 976
          http://www.exim.org/viewvc/pcre2?view=rev&revision=976
Author:   ph10
Date:     2018-07-28 17:23:24 +0100 (Sat, 28 Jul 2018)
Log Message:
-----------
Add support for (?^) as now supported by Perl.


Modified Paths:
--------------
    code/trunk/ChangeLog
    code/trunk/doc/html/pcre2api.html
    code/trunk/doc/html/pcre2compat.html
    code/trunk/doc/html/pcre2pattern.html
    code/trunk/doc/html/pcre2syntax.html
    code/trunk/doc/pcre2.txt
    code/trunk/doc/pcre2pattern.3
    code/trunk/doc/pcre2syntax.3
    code/trunk/src/pcre2.h.in
    code/trunk/src/pcre2_compile.c
    code/trunk/src/pcre2_error.c
    code/trunk/testdata/testinput1
    code/trunk/testdata/testinput2
    code/trunk/testdata/testoutput1
    code/trunk/testdata/testoutput2


Modified: code/trunk/ChangeLog
===================================================================
--- code/trunk/ChangeLog    2018-07-28 15:08:22 UTC (rev 975)
+++ code/trunk/ChangeLog    2018-07-28 16:23:24 UTC (rev 976)
@@ -131,6 +131,8 @@
 terminated by (*ACCEPT).


29. Add support for \N{U+dddd}, but not in EBCDIC environments.
+
+30. Add support for (?^) for unsetting all imnsx options.


Version 10.31 12-February-2018

Modified: code/trunk/doc/html/pcre2api.html
===================================================================
--- code/trunk/doc/html/pcre2api.html    2018-07-28 15:08:22 UTC (rev 975)
+++ code/trunk/doc/html/pcre2api.html    2018-07-28 16:23:24 UTC (rev 976)
@@ -1466,7 +1466,8 @@
 not match when the current position in the subject is at a newline. This option
 is equivalent to Perl's /s option, and it can be changed within a pattern by a
 (?s) option setting. A negative class such as [^a] always matches newline
-characters, independent of the setting of this option.
+characters, and the \N escape sequence always matches a non-newline character,
+independent of the setting of PCRE2_DOTALL.
 <pre>
   PCRE2_DUPNAMES
 </pre>
@@ -3634,7 +3635,7 @@
 </P>
 <br><a name="SEC42" href="#TOC1">REVISION</a><br>
 <P>
-Last updated: 02 July 2018
+Last updated: 27 July 2018
 <br>
 Copyright &copy; 1997-2018 University of Cambridge.
 <br>


Modified: code/trunk/doc/html/pcre2compat.html
===================================================================
--- code/trunk/doc/html/pcre2compat.html    2018-07-28 15:08:22 UTC (rev 975)
+++ code/trunk/doc/html/pcre2compat.html    2018-07-28 16:23:24 UTC (rev 976)
@@ -42,13 +42,14 @@
 false).
 </P>
 <P>
-4. The following Perl escape sequences are not supported: \l, \u, \L,
-\U, and \N when followed by a character name or Unicode value. (\N on its
-own, matching a non-newline character, is supported.) In fact these are
+4. The following Perl escape sequences are not supported: \F, \l, \L, \u, 
+\U, and \N when followed by a character name. \N on its own, matching a
+non-newline character, and \N{U+dd..}, matching a Unicode code point, are
+supported. The escapes that modify the case of following letters are
 implemented by Perl's general string-handling and are not part of its pattern
 matching engine. If any of these are encountered by PCRE2, an error is
-generated by default. However, if the PCRE2_ALT_BSUX option is set,
-\U and \u are interpreted as ECMAScript interprets them.
+generated by default. However, if the PCRE2_ALT_BSUX option is set, \U and \u
+are interpreted as ECMAScript interprets them.
 </P>
 <P>
 5. The Perl escape sequences \p, \P, and \X are supported only if PCRE2 is
@@ -61,17 +62,22 @@
 the somewhat messy concept of surrogates."
 </P>
 <P>
-6. PCRE2 does support the \Q...\E escape for quoting substrings. Characters
-in between are treated as literals. This is slightly different from Perl in
-that $ and @ are also handled as literals inside the quotes. In Perl, they
-cause variable interpolation (but of course PCRE2 does not have variables).
-Note the following examples:
+6. PCRE2 supports the \Q...\E escape for quoting substrings. Characters
+in between are treated as literals. However, this is slightly different from
+Perl in that $ and @ are also handled as literals inside the quotes. In Perl,
+they cause variable interpolation (but of course PCRE2 does not have
+variables). Also, Perl does "double-quotish backslash interpolation" on any
+backslashes between \Q and \E which, its documentation says, "may lead to
+confusing results". PCRE2 treats a backslash between \Q and \E just like any
+other character. Note the following examples:
 <pre>
-    Pattern            PCRE2 matches      Perl matches
+    Pattern            PCRE2 matches     Perl matches


     \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
     \Qabc\$xyz\E       abc\$xyz          abc\$xyz
     \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
+    \QA\B\E            A\B               A\B
+    \Q\\E              \                 \\E
 </pre>
 The \Q...\E sequence is recognized both inside and outside character classes.
 </P>
@@ -229,9 +235,9 @@
 REVISION
 </b><br>
 <P>
-Last updated: 18 April 2017
+Last updated: 28 July 2018
 <br>
-Copyright &copy; 1997-2017 University of Cambridge.
+Copyright &copy; 1997-2018 University of Cambridge.
 <br>
 <p>
 Return to the <a href="index.html">PCRE2 index page</a>.


Modified: code/trunk/doc/html/pcre2pattern.html
===================================================================
--- code/trunk/doc/html/pcre2pattern.html    2018-07-28 15:08:22 UTC (rev 975)
+++ code/trunk/doc/html/pcre2pattern.html    2018-07-28 16:23:24 UTC (rev 976)
@@ -357,7 +357,10 @@
 If you want to remove the special meaning from a sequence of characters, you
 can do so by putting them between \Q and \E. This is different from Perl in
 that $ and @ are handled as literals in \Q...\E sequences in PCRE2, whereas
-in Perl, $ and @ cause variable interpolation. Note the following examples:
+in Perl, $ and @ cause variable interpolation. Also, Perl does "double-quotish 
+backslash interpolation" on any backslashes between \Q and \E which, its
+documentation says, "may lead to confusing results". PCRE2 treats a backslash
+between \Q and \E just like any other character. Note the following examples:
 <pre>
   Pattern            PCRE2 matches   Perl matches


@@ -364,6 +367,8 @@
   \Qabc$xyz\E        abc$xyz        abc followed by the contents of $xyz
   \Qabc\$xyz\E       abc\$xyz       abc\$xyz
   \Qabc\E\$\Qxyz\E   abc$xyz        abc$xyz
+  \QA\B\E            A\B            A\B
+  \Q\\E              \              \\E
 </pre>
 The \Q...\E sequence is recognized both inside and outside character classes.
 An isolated \E that is not preceded by \Q is ignored. If \Q is not followed
@@ -545,7 +550,7 @@
 Unsupported escape sequences
 </b><br>
 <P>
-In Perl, the sequences \l, \L, \u, and \U are recognized by its string
+In Perl, the sequences \F, \l, \L, \u, and \U are recognized by its string
 handler and used to modify the case of following characters. By default, PCRE2
 does not support these escape sequences. However, if the PCRE2_ALT_BSUX option
 is set, \U matches a "U" character, and \u can be used to define a character
@@ -1635,21 +1640,27 @@
   xx for PCRE2_EXTENDED_MORE
 </pre>
 For example, (?im) sets caseless, multiline matching. It is also possible to
-unset these options by preceding the letter with a hyphen. The two "extended"
-options are not independent; unsetting either one cancels the effects of both
-of them.
+unset these options by preceding the relevant letters with a hyphen, for 
+example (?-im). The two "extended" options are not independent; unsetting either
+one cancels the effects of both of them.
 </P>
 <P>
 A combined setting and unsetting such as (?im-sx), which sets PCRE2_CASELESS
 and PCRE2_MULTILINE while unsetting PCRE2_DOTALL and PCRE2_EXTENDED, is also
-permitted. If a letter appears both before and after the hyphen, the option is
-unset. An empty options setting "(?)" is allowed. Needless to say, it has no
-effect.
+permitted. Only one hyphen may appear in the options string. If a letter
+appears both before and after the hyphen, the option is unset. An empty options
+setting "(?)" is allowed. Needless to say, it has no effect.
 </P>
 <P>
+If the first character following (? is a circumflex, it causes all of the above 
+options to be unset. Thus, (?^) is equivalent to (?-imnsx). Letters may follow 
+the circumflex to cause some options to be re-instated, but a hyphen may not 
+appear.
+</P>
+<P>
 The PCRE2-specific options PCRE2_DUPNAMES and PCRE2_UNGREEDY can be changed in
 the same way as the Perl-compatible options by using the characters J and U
-respectively.
+respectively. However, these are not unset by (?^).
 </P>
 <P>
 When one of these option changes occurs at top level (that is, not inside
@@ -3579,7 +3590,7 @@
 </P>
 <br><a name="SEC30" href="#TOC1">REVISION</a><br>
 <P>
-Last updated: 27 July 2018
+Last updated: 28 July 2018
 <br>
 Copyright &copy; 1997-2018 University of Cambridge.
 <br>


Modified: code/trunk/doc/html/pcre2syntax.html
===================================================================
--- code/trunk/doc/html/pcre2syntax.html    2018-07-28 15:08:22 UTC (rev 975)
+++ code/trunk/doc/html/pcre2syntax.html    2018-07-28 16:23:24 UTC (rev 976)
@@ -456,7 +456,15 @@
   (?x)            extended: ignore white space except in classes
   (?xx)           as (?x) but also ignore space and tab in classes
   (?-...)         unset option(s)
+  (?^)            unset imnsx options 
 </pre>
+Unsetting x or xx unsets both. Several options may be set at once, and a
+mixture of setting and unsetting such as (?i-x) is allowed, but there may be
+only one hyphen. Setting (but no unsetting) is allowed after (?^ for example
+(?^in). An option setting may appear at the start of a non-capturing group, for 
+example (?i:...).
+</P>
+<P>
 The following are recognized only at the very start of a pattern or after one
 of the newline or \R options with similar syntax. More than one of them may
 appear. For the first three, d is a decimal number.
@@ -624,7 +632,7 @@
 </P>
 <br><a name="SEC27" href="#TOC1">REVISION</a><br>
 <P>
-Last updated: 27 July 2018
+Last updated: 28 July 2018
 <br>
 Copyright &copy; 1997-2018 University of Cambridge.
 <br>


Modified: code/trunk/doc/pcre2.txt
===================================================================
--- code/trunk/doc/pcre2.txt    2018-07-28 15:08:22 UTC (rev 975)
+++ code/trunk/doc/pcre2.txt    2018-07-28 16:23:24 UTC (rev 976)
@@ -1454,276 +1454,277 @@
        this option, a dot does not match when the current position in the sub-
        ject is at a newline. This option is equivalent to  Perl's  /s  option,
        and it can be changed within a pattern by a (?s) option setting. A neg-
-       ative class such as [^a] always matches newline characters, independent
-       of the setting of this option.
+       ative class such as [^a] always matches newline characters, and the  \N
+       escape  sequence always matches a non-newline character, independent of
+       the setting of PCRE2_DOTALL.


          PCRE2_DUPNAMES


-       If  this  bit is set, names used to identify capturing subpatterns need
+       If this bit is set, names used to identify capturing  subpatterns  need
        not be unique. This can be helpful for certain types of pattern when it
-       is  known  that  only  one instance of the named subpattern can ever be
-       matched. There are more details of named subpatterns  below;  see  also
+       is known that only one instance of the named  subpattern  can  ever  be
+       matched.  There  are  more details of named subpatterns below; see also
        the pcre2pattern documentation.


          PCRE2_ENDANCHORED


-       If  this  bit is set, the end of any pattern match must be right at the
+       If this bit is set, the end of any pattern match must be right  at  the
        end of the string being searched (the "subject string"). If the pattern
        match succeeds by reaching (*ACCEPT), but does not reach the end of the
-       subject, the match fails at the current starting point. For  unanchored
-       patterns,  a  new  match is then tried at the next starting point. How-
+       subject,  the match fails at the current starting point. For unanchored
+       patterns, a new match is then tried at the next  starting  point.  How-
        ever, if the match succeeds by reaching the end of the pattern, but not
-       the  end  of  the subject, backtracking occurs and an alternative match
+       the end of the subject, backtracking occurs and  an  alternative  match
        may be found. Consider these two patterns:


          .(*ACCEPT)|..
          .|..


-       If matched against "abc" with PCRE2_ENDANCHORED set, the first  matches
-       "c"  whereas  the  second matches "bc". The effect of PCRE2_ENDANCHORED
-       can also be achieved by appropriate constructs in the  pattern  itself,
+       If  matched against "abc" with PCRE2_ENDANCHORED set, the first matches
+       "c" whereas the second matches "bc". The  effect  of  PCRE2_ENDANCHORED
+       can  also  be achieved by appropriate constructs in the pattern itself,
        which is the only way to do it in Perl.


        For DFA matching with pcre2_dfa_match(), PCRE2_ENDANCHORED applies only
-       to the first (that is, the  longest)  matched  string.  Other  parallel
-       matches,  which are necessarily substrings of the first one, must obvi-
+       to  the  first  (that  is,  the longest) matched string. Other parallel
+       matches, which are necessarily substrings of the first one, must  obvi-
        ously end before the end of the subject.


          PCRE2_EXTENDED


-       If this bit is set, most white space  characters  in  the  pattern  are
-       totally  ignored  except when escaped or inside a character class. How-
-       ever, white space is not allowed within  sequences  such  as  (?>  that
+       If  this  bit  is  set,  most white space characters in the pattern are
+       totally ignored except when escaped or inside a character  class.  How-
+       ever,  white  space  is  not  allowed within sequences such as (?> that
        introduce various parenthesized subpatterns, nor within numerical quan-
-       tifiers such as {1,3}.  Ignorable white space is permitted  between  an
-       item  and a following quantifier and between a quantifier and a follow-
+       tifiers  such  as {1,3}.  Ignorable white space is permitted between an
+       item and a following quantifier and between a quantifier and a  follow-
        ing + that indicates possessiveness.


-       PCRE2_EXTENDED also causes characters between an unescaped # outside  a
-       character  class  and the next newline, inclusive, to be ignored, which
+       PCRE2_EXTENDED  also causes characters between an unescaped # outside a
+       character class and the next newline, inclusive, to be  ignored,  which
        makes it possible to include comments inside complicated patterns. Note
-       that  the  end of this type of comment is a literal newline sequence in
+       that the end of this type of comment is a literal newline  sequence  in
        the pattern; escape sequences that happen to represent a newline do not
-       count.  PCRE2_EXTENDED is equivalent to Perl's /x option, and it can be
+       count. PCRE2_EXTENDED is equivalent to Perl's /x option, and it can  be
        changed within a pattern by a (?x) option setting.


        Which characters are interpreted as newlines can be specified by a set-
-       ting  in  the compile context that is passed to pcre2_compile() or by a
-       special sequence at the start of the pattern, as described in the  sec-
-       tion  entitled "Newline conventions" in the pcre2pattern documentation.
+       ting in the compile context that is passed to pcre2_compile() or  by  a
+       special  sequence at the start of the pattern, as described in the sec-
+       tion entitled "Newline conventions" in the pcre2pattern  documentation.
        A default is defined when PCRE2 is built.


          PCRE2_EXTENDED_MORE


-       This option  has  the  effect  of  PCRE2_EXTENDED,  but,  in  addition,
-       unescaped  space  and  horizontal  tab  characters are ignored inside a
-       character class.  PCRE2_EXTENDED_MORE is equivalent to Perl's 5.26  /xx
-       option,  and  it can be changed within a pattern by a (?xx) option set-
+       This  option  has  the  effect  of  PCRE2_EXTENDED,  but,  in addition,
+       unescaped space and horizontal tab  characters  are  ignored  inside  a
+       character  class.  PCRE2_EXTENDED_MORE is equivalent to Perl's 5.26 /xx
+       option, and it can be changed within a pattern by a (?xx)  option  set-
        ting.


          PCRE2_FIRSTLINE


        If this option is set, the start of an unanchored pattern match must be
-       before  or  at  the  first  newline in the subject string following the
-       start of matching, though the matched text may continue over  the  new-
+       before or at the first newline in  the  subject  string  following  the
+       start  of  matching, though the matched text may continue over the new-
        line. If startoffset is non-zero, the limiting newline is not necessar-
-       ily the first newline in the  subject.  For  example,  if  the  subject
+       ily  the  first  newline  in  the  subject. For example, if the subject
        string is "abc\nxyz" (where \n represents a single-character newline) a
-       pattern match for "yz" succeeds with PCRE2_FIRSTLINE if startoffset  is
-       greater  than 3. See also PCRE2_USE_OFFSET_LIMIT, which provides a more
-       general limiting facility. If PCRE2_FIRSTLINE is  set  with  an  offset
-       limit,  a match must occur in the first line and also within the offset
+       pattern  match for "yz" succeeds with PCRE2_FIRSTLINE if startoffset is
+       greater than 3. See also PCRE2_USE_OFFSET_LIMIT, which provides a  more
+       general  limiting  facility.  If  PCRE2_FIRSTLINE is set with an offset
+       limit, a match must occur in the first line and also within the  offset
        limit. In other words, whichever limit comes first is used.


          PCRE2_LITERAL


        If this option is set, all meta-characters in the pattern are disabled,
-       and  it is treated as a literal string. Matching literal strings with a
+       and it is treated as a literal string. Matching literal strings with  a
        regular expression engine is not the most efficient way of doing it. If
-       you  are  doing  a  lot of literal matching and are worried about effi-
+       you are doing a lot of literal matching and  are  worried  about  effi-
        ciency, you should consider using other approaches. The only other main
        options  that  are  allowed  with  PCRE2_LITERAL  are:  PCRE2_ANCHORED,
        PCRE2_ENDANCHORED, PCRE2_AUTO_CALLOUT, PCRE2_CASELESS, PCRE2_FIRSTLINE,
        PCRE2_NO_START_OPTIMIZE,     PCRE2_NO_UTF_CHECK,     PCRE2_UTF,     and
-       PCRE2_USE_OFFSET_LIMIT. The extra  options  PCRE2_EXTRA_MATCH_LINE  and
-       PCRE2_EXTRA_MATCH_WORD  are  also supported. Any other options cause an
+       PCRE2_USE_OFFSET_LIMIT.  The  extra  options PCRE2_EXTRA_MATCH_LINE and
+       PCRE2_EXTRA_MATCH_WORD are also supported. Any other options  cause  an
        error.


          PCRE2_MATCH_UNSET_BACKREF


-       If this option is set, a backreference to  an  unset  subpattern  group
-       matches  an  empty  string (by default this causes the current matching
-       alternative to fail).  A pattern such as  (\1)(a)  succeeds  when  this
-       option  is set (assuming it can find an "a" in the subject), whereas it
-       fails by default, for Perl compatibility.  Setting  this  option  makes
+       If  this  option  is  set, a backreference to an unset subpattern group
+       matches an empty string (by default this causes  the  current  matching
+       alternative  to  fail).   A  pattern such as (\1)(a) succeeds when this
+       option is set (assuming it can find an "a" in the subject), whereas  it
+       fails  by  default,  for  Perl compatibility. Setting this option makes
        PCRE2 behave more like ECMAscript (aka JavaScript).


          PCRE2_MULTILINE


-       By  default,  for  the purposes of matching "start of line" and "end of
-       line", PCRE2 treats the subject string as consisting of a  single  line
-       of  characters,  even  if  it actually contains newlines. The "start of
-       line" metacharacter (^) matches only at the start of  the  string,  and
-       the  "end  of  line"  metacharacter  ($) matches only at the end of the
+       By default, for the purposes of matching "start of line"  and  "end  of
+       line",  PCRE2  treats the subject string as consisting of a single line
+       of characters, even if it actually contains  newlines.  The  "start  of
+       line"  metacharacter  (^)  matches only at the start of the string, and
+       the "end of line" metacharacter ($) matches only  at  the  end  of  the
        string,  or  before  a  terminating  newline  (except  when  PCRE2_DOL-
-       LAR_ENDONLY  is  set).  Note, however, that unless PCRE2_DOTALL is set,
+       LAR_ENDONLY is set). Note, however, that unless  PCRE2_DOTALL  is  set,
        the "any character" metacharacter (.) does not match at a newline. This
        behaviour (for ^, $, and dot) is the same as Perl.


-       When  PCRE2_MULTILINE  it is set, the "start of line" and "end of line"
-       constructs match immediately following or immediately  before  internal
-       newlines  in  the  subject string, respectively, as well as at the very
-       start and end. This is equivalent to Perl's /m option, and  it  can  be
+       When PCRE2_MULTILINE it is set, the "start of line" and "end  of  line"
+       constructs  match  immediately following or immediately before internal
+       newlines in the subject string, respectively, as well as  at  the  very
+       start  and  end.  This is equivalent to Perl's /m option, and it can be
        changed within a pattern by a (?m) option setting. Note that the "start
        of line" metacharacter does not match after a newline at the end of the
-       subject,  for compatibility with Perl.  However, you can change this by
-       setting the PCRE2_ALT_CIRCUMFLEX option. If there are no newlines in  a
-       subject  string,  or  no  occurrences  of  ^ or $ in a pattern, setting
+       subject, for compatibility with Perl.  However, you can change this  by
+       setting  the PCRE2_ALT_CIRCUMFLEX option. If there are no newlines in a
+       subject string, or no occurrences of ^  or  $  in  a  pattern,  setting
        PCRE2_MULTILINE has no effect.


          PCRE2_NEVER_BACKSLASH_C


-       This option locks out the use of \C in the pattern that is  being  com-
-       piled.   This  escape  can  cause  unpredictable  behaviour in UTF-8 or
-       UTF-16 modes, because it may leave the current matching  point  in  the
-       middle  of  a  multi-code-unit  character. This option may be useful in
-       applications that process patterns from  external  sources.  Note  that
+       This  option  locks out the use of \C in the pattern that is being com-
+       piled.  This escape can  cause  unpredictable  behaviour  in  UTF-8  or
+       UTF-16  modes,  because  it may leave the current matching point in the
+       middle of a multi-code-unit character. This option  may  be  useful  in
+       applications  that  process  patterns  from external sources. Note that
        there is also a build-time option that permanently locks out the use of
        \C.


          PCRE2_NEVER_UCP


-       This option locks out the use of Unicode properties  for  handling  \B,
+       This  option  locks  out the use of Unicode properties for handling \B,
        \b, \D, \d, \S, \s, \W, \w, and some of the POSIX character classes, as
-       described for the PCRE2_UCP option below. In  particular,  it  prevents
-       the  creator of the pattern from enabling this facility by starting the
-       pattern with (*UCP). This option may be  useful  in  applications  that
+       described  for  the  PCRE2_UCP option below. In particular, it prevents
+       the creator of the pattern from enabling this facility by starting  the
+       pattern  with  (*UCP).  This  option may be useful in applications that
        process patterns from external sources. The option combination PCRE_UCP
        and PCRE_NEVER_UCP causes an error.


          PCRE2_NEVER_UTF


-       This option locks out interpretation of the pattern as  UTF-8,  UTF-16,
+       This  option  locks out interpretation of the pattern as UTF-8, UTF-16,
        or UTF-32, depending on which library is in use. In particular, it pre-
-       vents the creator of the pattern from switching to  UTF  interpretation
-       by  starting  the  pattern  with  (*UTF).  This option may be useful in
-       applications that process patterns from external sources. The  combina-
+       vents  the  creator of the pattern from switching to UTF interpretation
+       by starting the pattern with (*UTF).  This  option  may  be  useful  in
+       applications  that process patterns from external sources. The combina-
        tion of PCRE2_UTF and PCRE2_NEVER_UTF causes an error.


          PCRE2_NO_AUTO_CAPTURE


        If this option is set, it disables the use of numbered capturing paren-
-       theses in the pattern. Any opening parenthesis that is not followed  by
-       ?  behaves as if it were followed by ?: but named parentheses can still
+       theses  in the pattern. Any opening parenthesis that is not followed by
+       ? behaves as if it were followed by ?: but named parentheses can  still
        be used for capturing (and they acquire numbers in the usual way). This
-       is  the  same as Perl's /n option.  Note that, when this option is set,
-       references to capturing groups (backreferences or  recursion/subroutine
-       calls)  may  only refer to named groups, though the reference can be by
+       is the same as Perl's /n option.  Note that, when this option  is  set,
+       references  to capturing groups (backreferences or recursion/subroutine
+       calls) may only refer to named groups, though the reference can  be  by
        name or by number.


          PCRE2_NO_AUTO_POSSESS


        If this option is set, it disables "auto-possessification", which is an
-       optimization  that,  for example, turns a+b into a++b in order to avoid
-       backtracks into a+ that can never be successful. However,  if  callouts
-       are  in  use,  auto-possessification means that some callouts are never
+       optimization that, for example, turns a+b into a++b in order  to  avoid
+       backtracks  into  a+ that can never be successful. However, if callouts
+       are in use, auto-possessification means that some  callouts  are  never
        taken. You can set this option if you want the matching functions to do
-       a  full  unoptimized  search and run all the callouts, but it is mainly
+       a full unoptimized search and run all the callouts, but  it  is  mainly
        provided for testing purposes.


          PCRE2_NO_DOTSTAR_ANCHOR


        If this option is set, it disables an optimization that is applied when
-       .*  is  the  first significant item in a top-level branch of a pattern,
-       and all the other branches also start with .* or with \A or  \G  or  ^.
-       The  optimization  is  automatically disabled for .* if it is inside an
-       atomic group or a capturing group that is the subject of  a  backrefer-
-       ence,  or  if  the pattern contains (*PRUNE) or (*SKIP). When the opti-
-       mization is not disabled, such a pattern is automatically  anchored  if
+       .* is the first significant item in a top-level branch  of  a  pattern,
+       and  all  the  other branches also start with .* or with \A or \G or ^.
+       The optimization is automatically disabled for .* if it  is  inside  an
+       atomic  group  or a capturing group that is the subject of a backrefer-
+       ence, or if the pattern contains (*PRUNE) or (*SKIP).  When  the  opti-
+       mization  is  not disabled, such a pattern is automatically anchored if
        PCRE2_DOTALL is set for all the .* items and PCRE2_MULTILINE is not set
-       for any ^ items. Otherwise, the fact that any match must  start  either
-       at  the start of the subject or following a newline is remembered. Like
+       for  any  ^ items. Otherwise, the fact that any match must start either
+       at the start of the subject or following a newline is remembered.  Like
        other optimizations, this can cause callouts to be skipped.


          PCRE2_NO_START_OPTIMIZE


-       This is an option whose main effect is at matching time.  It  does  not
+       This  is  an  option whose main effect is at matching time. It does not
        change what pcre2_compile() generates, but it does affect the output of
        the JIT compiler.


-       There are a number of optimizations that may occur at the  start  of  a
-       match,  in  order  to speed up the process. For example, if it is known
-       that an unanchored match must start with a specific  code  unit  value,
-       the  matching code searches the subject for that value, and fails imme-
-       diately if it cannot find it, without actually running the main  match-
-       ing  function.  This means that a special item such as (*COMMIT) at the
-       start of a pattern is not considered until after  a  suitable  starting
-       point  for  the  match  has  been found. Also, when callouts or (*MARK)
-       items are in use, these "start-up" optimizations can cause them  to  be
-       skipped  if  the pattern is never actually used. The start-up optimiza-
-       tions are in effect a pre-scan of the subject that takes  place  before
+       There  are  a  number of optimizations that may occur at the start of a
+       match, in order to speed up the process. For example, if  it  is  known
+       that  an  unanchored  match must start with a specific code unit value,
+       the matching code searches the subject for that value, and fails  imme-
+       diately  if it cannot find it, without actually running the main match-
+       ing function. This means that a special item such as (*COMMIT)  at  the
+       start  of  a  pattern is not considered until after a suitable starting
+       point for the match has been found.  Also,  when  callouts  or  (*MARK)
+       items  are  in use, these "start-up" optimizations can cause them to be
+       skipped if the pattern is never actually used. The  start-up  optimiza-
+       tions  are  in effect a pre-scan of the subject that takes place before
        the pattern is run.


        The PCRE2_NO_START_OPTIMIZE option disables the start-up optimizations,
-       possibly causing performance to suffer,  but  ensuring  that  in  cases
-       where  the  result is "no match", the callouts do occur, and that items
+       possibly  causing  performance  to  suffer,  but ensuring that in cases
+       where the result is "no match", the callouts do occur, and  that  items
        such as (*COMMIT) and (*MARK) are considered at every possible starting
        position in the subject string.


-       Setting  PCRE2_NO_START_OPTIMIZE  may  change the outcome of a matching
+       Setting PCRE2_NO_START_OPTIMIZE may change the outcome  of  a  matching
        operation.  Consider the pattern


          (*COMMIT)ABC


-       When this is compiled, PCRE2 records the fact that a match  must  start
-       with  the  character  "A".  Suppose the subject string is "DEFABC". The
-       start-up optimization scans along the subject, finds "A" and  runs  the
-       first  match attempt from there. The (*COMMIT) item means that the pat-
-       tern must match the current starting position, which in this  case,  it
-       does.  However,  if  the same match is run with PCRE2_NO_START_OPTIMIZE
-       set, the initial scan along the subject string  does  not  happen.  The
-       first  match  attempt  is  run  starting  from "D" and when this fails,
-       (*COMMIT) prevents any further matches  being  tried,  so  the  overall
+       When  this  is compiled, PCRE2 records the fact that a match must start
+       with the character "A". Suppose the subject  string  is  "DEFABC".  The
+       start-up  optimization  scans along the subject, finds "A" and runs the
+       first match attempt from there. The (*COMMIT) item means that the  pat-
+       tern  must  match the current starting position, which in this case, it
+       does. However, if the same match is  run  with  PCRE2_NO_START_OPTIMIZE
+       set,  the  initial  scan  along the subject string does not happen. The
+       first match attempt is run starting  from  "D"  and  when  this  fails,
+       (*COMMIT)  prevents  any  further  matches  being tried, so the overall
        result is "no match".


-       There  are  also  other  start-up optimizations. For example, a minimum
+       There are also other start-up optimizations.  For  example,  a  minimum
        length for the subject may be recorded. Consider the pattern


          (*MARK:A)(X|Y)


-       The minimum length for a match is one  character.  If  the  subject  is
+       The  minimum  length  for  a  match is one character. If the subject is
        "ABC", there will be attempts to match "ABC", "BC", and "C". An attempt
        to match an empty string at the end of the subject does not take place,
-       because  PCRE2  knows  that  the  subject  is now too short, and so the
-       (*MARK) is never encountered. In this case, the optimization  does  not
+       because PCRE2 knows that the subject is  now  too  short,  and  so  the
+       (*MARK)  is  never encountered. In this case, the optimization does not
        affect the overall match result, which is still "no match", but it does
        affect the auxiliary information that is returned.


          PCRE2_NO_UTF_CHECK


-       When PCRE2_UTF is set, the validity of the pattern as a UTF  string  is
-       automatically  checked.  There  are  discussions  about the validity of
-       UTF-8 strings, UTF-16 strings, and UTF-32 strings in  the  pcre2unicode
-       document.  If an invalid UTF sequence is found, pcre2_compile() returns
+       When  PCRE2_UTF  is set, the validity of the pattern as a UTF string is
+       automatically checked. There are  discussions  about  the  validity  of
+       UTF-8  strings,  UTF-16 strings, and UTF-32 strings in the pcre2unicode
+       document. If an invalid UTF sequence is found, pcre2_compile()  returns
        a negative error code.


-       If you know that your pattern is a valid UTF string, and  you  want  to
-       skip   this   check   for   performance   reasons,   you  can  set  the
-       PCRE2_NO_UTF_CHECK option. When it is set, the  effect  of  passing  an
+       If  you  know  that your pattern is a valid UTF string, and you want to
+       skip  this  check  for   performance   reasons,   you   can   set   the
+       PCRE2_NO_UTF_CHECK  option.  When  it  is set, the effect of passing an
        invalid UTF string as a pattern is undefined. It may cause your program
        to crash or loop.


        Note  that  this  option  can  also  be  passed  to  pcre2_match()  and
-       pcre_dfa_match(),  to  suppress  UTF  validity  checking of the subject
+       pcre_dfa_match(), to suppress UTF  validity  checking  of  the  subject
        string.


        Note also that setting PCRE2_NO_UTF_CHECK at compile time does not dis-
-       able  the error that is given if an escape sequence for an invalid Uni-
-       code code point is encountered in the pattern. In particular,  the  so-
-       called  "surrogate"  code points (0xd800 to 0xdfff) are invalid. If you
-       want to allow escape  sequences  such  as  \x{d800}  you  can  set  the
-       PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES  extra  option, as described in the
-       section entitled "Extra compile options" below.  However, this is  pos-
+       able the error that is given if an escape sequence for an invalid  Uni-
+       code  code  point is encountered in the pattern. In particular, the so-
+       called "surrogate" code points (0xd800 to 0xdfff) are invalid.  If  you
+       want  to  allow  escape  sequences  such  as  \x{d800}  you can set the
+       PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES extra option, as described  in  the
+       section  entitled "Extra compile options" below.  However, this is pos-
        sible only in UTF-8 and UTF-32 modes, because these values are not rep-
        resentable in UTF-16.


@@ -1730,106 +1731,106 @@
          PCRE2_UCP


        This option changes the way PCRE2 processes \B, \b, \D, \d, \S, \s, \W,
-       \w,  and  some  of  the POSIX character classes. By default, only ASCII
-       characters are recognized, but if PCRE2_UCP is set, Unicode  properties
-       are  used instead to classify characters. More details are given in the
+       \w, and some of the POSIX character classes.  By  default,  only  ASCII
+       characters  are recognized, but if PCRE2_UCP is set, Unicode properties
+       are used instead to classify characters. More details are given in  the
        section on generic character types in the pcre2pattern page. If you set
-       PCRE2_UCP,  matching one of the items it affects takes much longer. The
-       option is available only if PCRE2 has been compiled with  Unicode  sup-
+       PCRE2_UCP, matching one of the items it affects takes much longer.  The
+       option  is  available only if PCRE2 has been compiled with Unicode sup-
        port (which is the default).


          PCRE2_UNGREEDY


-       This  option  inverts  the "greediness" of the quantifiers so that they
-       are not greedy by default, but become greedy if followed by "?". It  is
-       not  compatible  with Perl. It can also be set by a (?U) option setting
+       This option inverts the "greediness" of the quantifiers  so  that  they
+       are  not greedy by default, but become greedy if followed by "?". It is
+       not compatible with Perl. It can also be set by a (?U)  option  setting
        within the pattern.


          PCRE2_USE_OFFSET_LIMIT


        This option must be set for pcre2_compile() if pcre2_set_offset_limit()
-       is  going  to be used to set a non-default offset limit in a match con-
-       text for matches that use this pattern. An error  is  generated  if  an
-       offset  limit  is  set  without  this option. For more details, see the
-       description of pcre2_set_offset_limit() in the section  that  describes
+       is going to be used to set a non-default offset limit in a  match  con-
+       text  for  matches  that  use this pattern. An error is generated if an
+       offset limit is set without this option.  For  more  details,  see  the
+       description  of  pcre2_set_offset_limit() in the section that describes
        match contexts. See also the PCRE2_FIRSTLINE option above.


          PCRE2_UTF


-       This  option  causes  PCRE2  to regard both the pattern and the subject
-       strings that are subsequently processed as strings  of  UTF  characters
-       instead  of  single-code-unit  strings.  It  is available when PCRE2 is
-       built to include Unicode support (which is  the  default).  If  Unicode
-       support  is  not  available,  the use of this option provokes an error.
-       Details of how PCRE2_UTF changes the behaviour of PCRE2  are  given  in
+       This option causes PCRE2 to regard both the  pattern  and  the  subject
+       strings  that  are  subsequently processed as strings of UTF characters
+       instead of single-code-unit strings. It  is  available  when  PCRE2  is
+       built  to  include  Unicode  support (which is the default). If Unicode
+       support is not available, the use of this  option  provokes  an  error.
+       Details  of  how  PCRE2_UTF changes the behaviour of PCRE2 are given in
        the pcre2unicode page.


    Extra compile options


-       Unlike  the  main compile-time options, the extra options are not saved
+       Unlike the main compile-time options, the extra options are  not  saved
        with the compiled pattern. The option bits that can be set in a compile
-       context  by  calling the pcre2_set_compile_extra_options() function are
+       context by calling the pcre2_set_compile_extra_options()  function  are
        as follows:


          PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES


-       This option applies when compiling a pattern in UTF-8 or  UTF-32  mode.
-       It  is  forbidden in UTF-16 mode, and ignored in non-UTF modes. Unicode
+       This  option  applies when compiling a pattern in UTF-8 or UTF-32 mode.
+       It is forbidden in UTF-16 mode, and ignored in non-UTF  modes.  Unicode
        "surrogate" code points in the range 0xd800 to 0xdfff are used in pairs
-       in  UTF-16  to  encode  code points with values in the range 0x10000 to
-       0x10ffff. The surrogates cannot therefore  be  represented  in  UTF-16.
+       in UTF-16 to encode code points with values in  the  range  0x10000  to
+       0x10ffff.  The  surrogates  cannot  therefore be represented in UTF-16.
        They can be represented in UTF-8 and UTF-32, but are defined as invalid
-       code points, and cause errors if  encountered  in  a  UTF-8  or  UTF-32
+       code  points,  and  cause  errors  if  encountered in a UTF-8 or UTF-32
        string that is being checked for validity by PCRE2.


-       These  values also cause errors if encountered in escape sequences such
+       These values also cause errors if encountered in escape sequences  such
        as \x{d912} within a pattern. However, it seems that some applications,
-       when  using  PCRE2  to  check for unwanted characters in UTF-8 strings,
-       explicitly  test  for  the  surrogates  using  escape  sequences.   The
-       PCRE2_NO_UTF_CHECK  option  does  not  disable  the  error that occurs,
-       because it applies only to the testing of input strings for UTF  valid-
+       when using PCRE2 to check for unwanted  characters  in  UTF-8  strings,
+       explicitly   test  for  the  surrogates  using  escape  sequences.  The
+       PCRE2_NO_UTF_CHECK option does  not  disable  the  error  that  occurs,
+       because  it applies only to the testing of input strings for UTF valid-
        ity.


-       If  the extra option PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES is set, surro-
-       gate code point values in UTF-8 and UTF-32 patterns no  longer  provoke
-       errors  and are incorporated in the compiled pattern. However, they can
-       only match subject characters if the matching function is  called  with
+       If the extra option PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES is set,  surro-
+       gate  code  point values in UTF-8 and UTF-32 patterns no longer provoke
+       errors and are incorporated in the compiled pattern. However, they  can
+       only  match  subject characters if the matching function is called with
        PCRE2_NO_UTF_CHECK set.


          PCRE2_EXTRA_BAD_ESCAPE_IS_LITERAL


-       This  is a dangerous option. Use with care. By default, an unrecognized
-       escape such as \j or a malformed one such as \x{2z} causes  a  compile-
+       This is a dangerous option. Use with care. By default, an  unrecognized
+       escape  such  as \j or a malformed one such as \x{2z} causes a compile-
        time error when detected by pcre2_compile(). Perl is somewhat inconsis-
-       tent in handling such items: for example, \j is treated  as  a  literal
-       "j",  and non-hexadecimal digits in \x{} are just ignored, though warn-
-       ings are given in both cases if Perl's warning switch is enabled.  How-
-       ever,  a  malformed  octal  number  after \o{ always causes an error in
+       tent  in  handling  such items: for example, \j is treated as a literal
+       "j", and non-hexadecimal digits in \x{} are just ignored, though  warn-
+       ings  are given in both cases if Perl's warning switch is enabled. How-
+       ever, a malformed octal number after \o{  always  causes  an  error  in
        Perl.


-       If the PCRE2_EXTRA_BAD_ESCAPE_IS_LITERAL  extra  option  is  passed  to
-       pcre2_compile(),  all  unrecognized  or  erroneous escape sequences are
-       treated as single-character escapes. For example, \j is a  literal  "j"
-       and  \x{2z}  is  treated  as  the  literal string "x{2z}". Setting this
-       option means that typos in patterns may go undetected  and  have  unex-
+       If  the  PCRE2_EXTRA_BAD_ESCAPE_IS_LITERAL  extra  option  is passed to
+       pcre2_compile(), all unrecognized or  erroneous  escape  sequences  are
+       treated  as  single-character escapes. For example, \j is a literal "j"
+       and \x{2z} is treated as  the  literal  string  "x{2z}".  Setting  this
+       option  means  that  typos in patterns may go undetected and have unex-
        pected results. This is a dangerous option. Use with care.


          PCRE2_EXTRA_MATCH_LINE


-       This  option  is  provided  for  use  by the -x option of pcre2grep. It
-       causes the pattern only to match complete lines. This  is  achieved  by
-       automatically  inserting  the  code for "^(?:" at the start of the com-
-       piled pattern and ")$" at the end. Thus, when PCRE2_MULTILINE  is  set,
-       the  matched  line  may  be  in  the middle of the subject string. This
+       This option is provided for use by  the  -x  option  of  pcre2grep.  It
+       causes  the  pattern  only to match complete lines. This is achieved by
+       automatically inserting the code for "^(?:" at the start  of  the  com-
+       piled  pattern  and ")$" at the end. Thus, when PCRE2_MULTILINE is set,
+       the matched line may be in the  middle  of  the  subject  string.  This
        option can be used with PCRE2_LITERAL.


          PCRE2_EXTRA_MATCH_WORD


-       This option is provided for use by  the  -w  option  of  pcre2grep.  It
-       causes  the  pattern only to match strings that have a word boundary at
-       the start and the end. This is achieved by automatically inserting  the
-       code  for "\b(?:" at the start of the compiled pattern and ")\b" at the
-       end. The option may be used with PCRE2_LITERAL. However, it is  ignored
+       This  option  is  provided  for  use  by the -w option of pcre2grep. It
+       causes the pattern only to match strings that have a word  boundary  at
+       the  start and the end. This is achieved by automatically inserting the
+       code for "\b(?:" at the start of the compiled pattern and ")\b" at  the
+       end.  The option may be used with PCRE2_LITERAL. However, it is ignored
        if PCRE2_EXTRA_MATCH_LINE is also set.



@@ -1852,53 +1853,53 @@

        void pcre2_jit_stack_free(pcre2_jit_stack *jit_stack);


-       These  functions  provide  support  for  JIT compilation, which, if the
-       just-in-time compiler is available, further processes a  compiled  pat-
+       These functions provide support for  JIT  compilation,  which,  if  the
+       just-in-time  compiler  is available, further processes a compiled pat-
        tern into machine code that executes much faster than the pcre2_match()
-       interpretive matching function. Full details are given in the  pcre2jit
+       interpretive  matching function. Full details are given in the pcre2jit
        documentation.


-       JIT  compilation  is  a heavyweight optimization. It can take some time
-       for patterns to be analyzed, and for one-off matches  and  simple  pat-
-       terns  the benefit of faster execution might be offset by a much slower
-       compilation time.  Most (but not all) patterns can be optimized by  the
+       JIT compilation is a heavyweight optimization. It can  take  some  time
+       for  patterns  to  be analyzed, and for one-off matches and simple pat-
+       terns the benefit of faster execution might be offset by a much  slower
+       compilation  time.  Most (but not all) patterns can be optimized by the
        JIT compiler.



LOCALE SUPPORT

-       PCRE2  handles caseless matching, and determines whether characters are
-       letters, digits, or whatever, by reference to a set of tables,  indexed
-       by  character  code  point.  This applies only to characters whose code
-       points are less than 256. By default, higher-valued code  points  never
-       match  escapes  such as \w or \d.  However, if PCRE2 is built with Uni-
+       PCRE2 handles caseless matching, and determines whether characters  are
+       letters,  digits, or whatever, by reference to a set of tables, indexed
+       by character code point. This applies only  to  characters  whose  code
+       points  are  less than 256. By default, higher-valued code points never
+       match escapes such as \w or \d.  However, if PCRE2 is built  with  Uni-
        code support, all characters can be tested with \p and \P, or, alterna-
-       tively,  the  PCRE2_UCP  option  can be set when a pattern is compiled;
-       this causes \w and friends to use Unicode property support  instead  of
+       tively, the PCRE2_UCP option can be set when  a  pattern  is  compiled;
+       this  causes  \w and friends to use Unicode property support instead of
        the built-in tables.


-       The  use  of  locales  with Unicode is discouraged. If you are handling
-       characters with code points greater than 128,  you  should  either  use
+       The use of locales with Unicode is discouraged.  If  you  are  handling
+       characters  with  code  points  greater than 128, you should either use
        Unicode support, or use locales, but not try to mix the two.


-       PCRE2  contains  an  internal  set of character tables that are used by
-       default.  These are sufficient for  many  applications.  Normally,  the
+       PCRE2 contains an internal set of character tables  that  are  used  by
+       default.   These  are  sufficient  for many applications. Normally, the
        internal tables recognize only ASCII characters. However, when PCRE2 is
        built, it is possible to cause the internal tables to be rebuilt in the
        default "C" locale of the local system, which may cause them to be dif-
        ferent.


-       The internal tables can be overridden by tables supplied by the  appli-
-       cation  that  calls  PCRE2.  These may be created in a different locale
-       from the default.  As more and more applications change to  using  Uni-
+       The  internal tables can be overridden by tables supplied by the appli-
+       cation that calls PCRE2. These may be created  in  a  different  locale
+       from  the  default.  As more and more applications change to using Uni-
        code, the need for this locale support is expected to die away.


-       External  tables  are built by calling the pcre2_maketables() function,
-       in the relevant locale. The result can be passed to pcre2_compile()  as
-       often   as  necessary,  by  creating  a  compile  context  and  calling
-       pcre2_set_character_tables() to set the  tables  pointer  therein.  For
-       example,  to  build  and use tables that are appropriate for the French
-       locale (where accented characters with  values  greater  than  128  are
+       External tables are built by calling the  pcre2_maketables()  function,
+       in  the relevant locale. The result can be passed to pcre2_compile() as
+       often  as  necessary,  by  creating  a  compile  context  and   calling
+       pcre2_set_character_tables()  to  set  the  tables pointer therein. For
+       example, to build and use tables that are appropriate  for  the  French
+       locale  (where  accented  characters  with  values greater than 128 are
        treated as letters), the following code could be used:


          setlocale(LC_CTYPE, "fr_FR");
@@ -1907,15 +1908,15 @@
          pcre2_set_character_tables(ccontext, tables);
          re = pcre2_compile(..., ccontext);


-       The  locale  name "fr_FR" is used on Linux and other Unix-like systems;
-       if you are using Windows, the name for the French locale  is  "french".
-       It  is the caller's responsibility to ensure that the memory containing
+       The locale name "fr_FR" is used on Linux and other  Unix-like  systems;
+       if  you  are using Windows, the name for the French locale is "french".
+       It is the caller's responsibility to ensure that the memory  containing
        the tables remains available for as long as it is needed.


        The pointer that is passed (via the compile context) to pcre2_compile()
-       is  saved  with  the  compiled pattern, and the same tables are used by
-       pcre2_match() and pcre_dfa_match(). Thus, for any single pattern,  com-
-       pilation  and  matching  both  happen in the same locale, but different
+       is saved with the compiled pattern, and the same  tables  are  used  by
+       pcre2_match()  and pcre_dfa_match(). Thus, for any single pattern, com-
+       pilation and matching both happen in the  same  locale,  but  different
        patterns can be processed in different locales.



@@ -1923,13 +1924,13 @@

        int pcre2_pattern_info(const pcre2 *code, uint32_t what, void *where);


-       The pcre2_pattern_info() function returns general information  about  a
+       The  pcre2_pattern_info()  function returns general information about a
        compiled pattern. For information about callouts, see the next section.
-       The first argument for pcre2_pattern_info() is a pointer  to  the  com-
+       The  first  argument  for pcre2_pattern_info() is a pointer to the com-
        piled pattern. The second argument specifies which piece of information
-       is required, and the third argument is  a  pointer  to  a  variable  to
-       receive  the data. If the third argument is NULL, the first argument is
-       ignored, and the function returns the size in  bytes  of  the  variable
+       is  required,  and  the  third  argument  is a pointer to a variable to
+       receive the data. If the third argument is NULL, the first argument  is
+       ignored,  and  the  function  returns the size in bytes of the variable
        that is required for the information requested. Otherwise, the yield of
        the function is zero for success, or one of the following negative num-
        bers:
@@ -1939,9 +1940,9 @@
          PCRE2_ERROR_BADOPTION      the value of what was invalid
          PCRE2_ERROR_UNSET          the requested field is not set


-       The  "magic  number" is placed at the start of each compiled pattern as
-       an simple check against passing an arbitrary memory pointer. Here is  a
-       typical  call of pcre2_pattern_info(), to obtain the length of the com-
+       The "magic number" is placed at the start of each compiled  pattern  as
+       an  simple check against passing an arbitrary memory pointer. Here is a
+       typical call of pcre2_pattern_info(), to obtain the length of the  com-
        piled pattern:


          int rc;
@@ -1959,22 +1960,22 @@
          PCRE2_INFO_EXTRAOPTIONS


        Return copies of the pattern's options. The third argument should point
-       to a  uint32_t  variable.  PCRE2_INFO_ARGOPTIONS  returns  exactly  the
-       options  that were passed to pcre2_compile(), whereas PCRE2_INFO_ALLOP-
-       TIONS returns the compile options as modified by any  top-level  (*XXX)
-       option  settings  such  as  (*UTF)  at the start of the pattern itself.
-       PCRE2_INFO_EXTRAOPTIONS returns the extra options that were set in  the
-       compile  context by calling the pcre2_set_compile_extra_options() func-
+       to  a  uint32_t  variable.  PCRE2_INFO_ARGOPTIONS  returns  exactly the
+       options that were passed to pcre2_compile(), whereas  PCRE2_INFO_ALLOP-
+       TIONS  returns  the compile options as modified by any top-level (*XXX)
+       option settings such as (*UTF) at the  start  of  the  pattern  itself.
+       PCRE2_INFO_EXTRAOPTIONS  returns the extra options that were set in the
+       compile context by calling the pcre2_set_compile_extra_options()  func-
        tion.


-       For  example,  if  the  pattern  /(*UTF)abc/  is  compiled   with   the
-       PCRE2_EXTENDED   option,   the   result  for  PCRE2_INFO_ALLOPTIONS  is
-       PCRE2_EXTENDED and PCRE2_UTF.  Option settings such as  (?i)  that  can
-       change  within  a pattern do not affect the result of PCRE2_INFO_ALLOP-
+       For   example,   if  the  pattern  /(*UTF)abc/  is  compiled  with  the
+       PCRE2_EXTENDED  option,  the  result   for   PCRE2_INFO_ALLOPTIONS   is
+       PCRE2_EXTENDED  and  PCRE2_UTF.   Option settings such as (?i) that can
+       change within a pattern do not affect the result  of  PCRE2_INFO_ALLOP-
        TIONS, even if they appear right at the start of the pattern. (This was
        different in some earlier releases.)


-       A  pattern compiled without PCRE2_ANCHORED is automatically anchored by
+       A pattern compiled without PCRE2_ANCHORED is automatically anchored  by
        PCRE2 if the first significant item in every top-level branch is one of
        the following:


@@ -1983,7 +1984,7 @@
          \G    always
          .*    sometimes - see below


-       When  .* is the first significant item, anchoring is possible only when
+       When .* is the first significant item, anchoring is possible only  when
        all the following are true:


          .* is not in an atomic group
@@ -1993,71 +1994,71 @@
          Neither (*PRUNE) nor (*SKIP) appears in the pattern
          PCRE2_NO_DOTSTAR_ANCHOR is not set


-       For patterns that are auto-anchored, the PCRE2_ANCHORED bit is  set  in
+       For  patterns  that are auto-anchored, the PCRE2_ANCHORED bit is set in
        the options returned for PCRE2_INFO_ALLOPTIONS.


          PCRE2_INFO_BACKREFMAX


-       Return  the  number  of  the  highest backreference in the pattern. The
-       third argument should point to an uint32_t variable. Named  subpatterns
-       acquire  numbers  as well as names, and these count towards the highest
-       backreference.  Backreferences such as \4 or \g{12} match the  captured
-       characters  of  the given group, but in addition, the check that a cap-
-       turing group is set in a conditional subpattern such  as  (?(3)a|b)  is
+       Return the number of the highest  backreference  in  the  pattern.  The
+       third  argument should point to an uint32_t variable. Named subpatterns
+       acquire numbers as well as names, and these count towards  the  highest
+       backreference.   Backreferences such as \4 or \g{12} match the captured
+       characters of the given group, but in addition, the check that  a  cap-
+       turing  group  is  set in a conditional subpattern such as (?(3)a|b) is
        also a backreference. Zero is returned if there are no backreferences.


          PCRE2_INFO_BSR


-       The  output  is a uint32_t integer whose value indicates what character
-       sequences the \R escape sequence matches. A value of  PCRE2_BSR_UNICODE
-       means  that  \R  matches  any  Unicode line ending sequence; a value of
+       The output is a uint32_t integer whose value indicates  what  character
+       sequences  the \R escape sequence matches. A value of PCRE2_BSR_UNICODE
+       means that \R matches any Unicode line  ending  sequence;  a  value  of
        PCRE2_BSR_ANYCRLF means that \R matches only CR, LF, or CRLF.


          PCRE2_INFO_CAPTURECOUNT


-       Return the highest capturing subpattern number in the pattern. In  pat-
+       Return  the highest capturing subpattern number in the pattern. In pat-
        terns where (?| is not used, this is also the total number of capturing
        subpatterns.  The third argument should point to an uint32_t variable.


          PCRE2_INFO_DEPTHLIMIT


-       If the pattern set a backtracking depth limit by including an  item  of
-       the  form  (*LIMIT_DEPTH=nnnn) at the start, the value is returned. The
+       If  the  pattern set a backtracking depth limit by including an item of
+       the form (*LIMIT_DEPTH=nnnn) at the start, the value is  returned.  The
        third argument should point to a uint32_t integer. If no such value has
-       been   set,   the   call  to  pcre2_pattern_info()  returns  the  error
+       been  set,  the  call  to  pcre2_pattern_info()   returns   the   error
        PCRE2_ERROR_UNSET. Note that this limit will only be used during match-
-       ing  if it is less than the limit set or defaulted by the caller of the
+       ing if it is less than the limit set or defaulted by the caller of  the
        match function.


          PCRE2_INFO_FIRSTBITMAP


-       In the absence of a single first code unit for a non-anchored  pattern,
-       pcre2_compile()  may construct a 256-bit table that defines a fixed set
-       of values for the first code unit in any match. For example, a  pattern
-       that  starts  with  [abc]  results in a table with three bits set. When
-       code unit values greater than 255 are supported, the flag bit  for  255
-       means  "any  code unit of value 255 or above". If such a table was con-
-       structed, a pointer to it is returned. Otherwise NULL is returned.  The
+       In  the absence of a single first code unit for a non-anchored pattern,
+       pcre2_compile() may construct a 256-bit table that defines a fixed  set
+       of  values for the first code unit in any match. For example, a pattern
+       that starts with [abc] results in a table with  three  bits  set.  When
+       code  unit  values greater than 255 are supported, the flag bit for 255
+       means "any code unit of value 255 or above". If such a table  was  con-
+       structed,  a pointer to it is returned. Otherwise NULL is returned. The
        third argument should point to a const uint8_t * variable.


          PCRE2_INFO_FIRSTCODETYPE


        Return information about the first code unit of any matched string, for
-       a non-anchored pattern. The third argument should point to an  uint32_t
-       variable.  If there is a fixed first value, for example, the letter "c"
-       from a pattern such as (cat|cow|coyote), 1 is returned, and  the  value
-       can  be  retrieved using PCRE2_INFO_FIRSTCODEUNIT. If there is no fixed
-       first value, but it is known that a match can occur only at  the  start
-       of  the  subject  or following a newline in the subject, 2 is returned.
+       a  non-anchored pattern. The third argument should point to an uint32_t
+       variable. If there is a fixed first value, for example, the letter  "c"
+       from  a  pattern such as (cat|cow|coyote), 1 is returned, and the value
+       can be retrieved using PCRE2_INFO_FIRSTCODEUNIT. If there is  no  fixed
+       first  value,  but it is known that a match can occur only at the start
+       of the subject or following a newline in the subject,  2  is  returned.
        Otherwise, and for anchored patterns, 0 is returned.


          PCRE2_INFO_FIRSTCODEUNIT


-       Return the value of the first code unit of any  matched  string  for  a
-       pattern  where  PCRE2_INFO_FIRSTCODETYPE returns 1; otherwise return 0.
-       The third argument should point to an uint32_t variable. In  the  8-bit
-       library,  the  value is always less than 256. In the 16-bit library the
-       value can be up to 0xffff. In the 32-bit library  in  UTF-32  mode  the
+       Return  the  value  of  the first code unit of any matched string for a
+       pattern where PCRE2_INFO_FIRSTCODETYPE returns 1; otherwise  return  0.
+       The  third  argument should point to an uint32_t variable. In the 8-bit
+       library, the value is always less than 256. In the 16-bit  library  the
+       value  can  be  up  to 0xffff. In the 32-bit library in UTF-32 mode the
        value can be up to 0x10ffff, and up to 0xffffffff when not using UTF-32
        mode.


@@ -2064,23 +2065,23 @@
          PCRE2_INFO_FRAMESIZE


        Return the size (in bytes) of the data frames that are used to remember
-       backtracking  positions  when the pattern is processed by pcre2_match()
-       without the use of JIT. The third argument should  point  to  a  size_t
+       backtracking positions when the pattern is processed  by  pcre2_match()
+       without  the  use  of  JIT. The third argument should point to a size_t
        variable. The frame size depends on the number of capturing parentheses
-       in the pattern. Each additional capturing  group  adds  two  PCRE2_SIZE
+       in  the  pattern.  Each  additional capturing group adds two PCRE2_SIZE
        variables.


          PCRE2_INFO_HASBACKSLASHC


-       Return  1 if the pattern contains any instances of \C, otherwise 0. The
+       Return 1 if the pattern contains any instances of \C, otherwise 0.  The
        third argument should point to an uint32_t variable.


          PCRE2_INFO_HASCRORLF


-       Return 1 if the pattern contains any explicit  matches  for  CR  or  LF
+       Return  1  if  the  pattern  contains any explicit matches for CR or LF
        characters, otherwise 0. The third argument should point to an uint32_t
-       variable. An explicit match is either a literal CR or LF character,  or
-       \r  or  \n  or  one  of  the  equivalent  hexadecimal  or  octal escape
+       variable.  An explicit match is either a literal CR or LF character, or
+       \r or  \n  or  one  of  the  equivalent  hexadecimal  or  octal  escape
        sequences.


          PCRE2_INFO_HEAPLIMIT
@@ -2088,81 +2089,81 @@
        If the pattern set a heap memory limit by including an item of the form
        (*LIMIT_HEAP=nnnn) at the start, the value is returned. The third argu-
        ment should point to a uint32_t integer. If no such value has been set,
-       the  call  to pcre2_pattern_info() returns the error PCRE2_ERROR_UNSET.
-       Note that this limit will only be used during matching if  it  is  less
+       the call to pcre2_pattern_info() returns the  error  PCRE2_ERROR_UNSET.
+       Note  that  this  limit will only be used during matching if it is less
        than the limit set or defaulted by the caller of the match function.


          PCRE2_INFO_JCHANGED


-       Return  1  if  the (?J) or (?-J) option setting is used in the pattern,
-       otherwise 0. The third argument should point to an  uint32_t  variable.
-       (?J)  and  (?-J) set and unset the local PCRE2_DUPNAMES option, respec-
+       Return 1 if the (?J) or (?-J) option setting is used  in  the  pattern,
+       otherwise  0.  The third argument should point to an uint32_t variable.
+       (?J) and (?-J) set and unset the local PCRE2_DUPNAMES  option,  respec-
        tively.


          PCRE2_INFO_JITSIZE


-       If the compiled pattern was successfully  processed  by  pcre2_jit_com-
-       pile(),  return  the  size  of  the JIT compiled code, otherwise return
+       If  the  compiled  pattern was successfully processed by pcre2_jit_com-
+       pile(), return the size of the  JIT  compiled  code,  otherwise  return
        zero. The third argument should point to a size_t variable.


          PCRE2_INFO_LASTCODETYPE


-       Returns 1 if there is a rightmost literal code unit that must exist  in
-       any  matched string, other than at its start. The third argument should
-       point to an uint32_t  variable.  If  there  is  no  such  value,  0  is
-       returned.  When  1  is  returned,  the  code  unit  value itself can be
-       retrieved using PCRE2_INFO_LASTCODEUNIT. For anchored patterns, a  last
-       literal  value  is  recorded  only  if it follows something of variable
-       length. For example, for the pattern /^a\d+z\d+/ the returned value  is
-       1  (with  "z" returned from PCRE2_INFO_LASTCODEUNIT), but for /^a\dz\d/
+       Returns  1 if there is a rightmost literal code unit that must exist in
+       any matched string, other than at its start. The third argument  should
+       point  to  an  uint32_t  variable.  If  there  is  no  such value, 0 is
+       returned. When 1 is  returned,  the  code  unit  value  itself  can  be
+       retrieved  using PCRE2_INFO_LASTCODEUNIT. For anchored patterns, a last
+       literal value is recorded only if  it  follows  something  of  variable
+       length.  For example, for the pattern /^a\d+z\d+/ the returned value is
+       1 (with "z" returned from PCRE2_INFO_LASTCODEUNIT), but  for  /^a\dz\d/
        the returned value is 0.


          PCRE2_INFO_LASTCODEUNIT


-       Return the value of the rightmost literal code unit that must exist  in
-       any  matched  string,  other  than  at  its  start, for a pattern where
+       Return  the value of the rightmost literal code unit that must exist in
+       any matched string, other than  at  its  start,  for  a  pattern  where
        PCRE2_INFO_LASTCODETYPE returns 1. Otherwise, return 0. The third argu-
        ment should point to an uint32_t variable.


          PCRE2_INFO_MATCHEMPTY


-       Return  1  if the pattern might match an empty string, otherwise 0. The
-       third argument should point to an uint32_t  variable.  When  a  pattern
+       Return 1 if the pattern might match an empty string, otherwise  0.  The
+       third  argument  should  point  to an uint32_t variable. When a pattern
        contains recursive subroutine calls it is not always possible to deter-
-       mine whether or not it can match an empty string. PCRE2  takes  a  cau-
+       mine  whether  or  not it can match an empty string. PCRE2 takes a cau-
        tious approach and returns 1 in such cases.


          PCRE2_INFO_MATCHLIMIT


-       If  the  pattern  set  a  match  limit by including an item of the form
-       (*LIMIT_MATCH=nnnn) at the start, the  value  is  returned.  The  third
-       argument  should point to a uint32_t integer. If no such value has been
-       set,   the   call   to   pcre2_pattern_info()   returns    the    error
+       If the pattern set a match limit by  including  an  item  of  the  form
+       (*LIMIT_MATCH=nnnn)  at  the  start,  the  value is returned. The third
+       argument should point to a uint32_t integer. If no such value has  been
+       set,    the    call   to   pcre2_pattern_info()   returns   the   error
        PCRE2_ERROR_UNSET. Note that this limit will only be used during match-
-       ing if it is less than the limit set or defaulted by the caller of  the
+       ing  if it is less than the limit set or defaulted by the caller of the
        match function.


          PCRE2_INFO_MAXLOOKBEHIND


        Return the number of characters (not code units) in the longest lookbe-
-       hind assertion in the pattern. The third argument  should  point  to  a
-       uint32_t  integer.  This information is useful when doing multi-segment
-       matching using the partial matching facilities. Note  that  the  simple
+       hind  assertion  in  the  pattern. The third argument should point to a
+       uint32_t integer. This information is useful when  doing  multi-segment
+       matching  using  the  partial matching facilities. Note that the simple
        assertions \b and \B require a one-character lookbehind. \A also regis-
-       ters a one-character lookbehind, though it does  not  actually  inspect
-       the  previous  character. This is to ensure that at least one character
-       from the old segment is retained when a new segment is processed.  Oth-
-       erwise,  if  there  are  no  lookbehinds in the pattern, \A might match
+       ters  a  one-character  lookbehind, though it does not actually inspect
+       the previous character. This is to ensure that at least  one  character
+       from  the old segment is retained when a new segment is processed. Oth-
+       erwise, if there are no lookbehinds in  the  pattern,  \A  might  match
        incorrectly at the start of a second or subsequent segment.


          PCRE2_INFO_MINLENGTH


-       If a minimum length for matching  subject  strings  was  computed,  its
-       value  is  returned.  Otherwise the returned value is 0. The value is a
-       number of characters, which in UTF mode may be different from the  num-
-       ber  of  code  units.   The  third argument should point to an uint32_t
-       variable. The value is a lower bound to  the  length  of  any  matching
-       string.  There  may  not be any strings of that length that do actually
+       If  a  minimum  length  for  matching subject strings was computed, its
+       value is returned. Otherwise the returned value is 0. The  value  is  a
+       number  of characters, which in UTF mode may be different from the num-
+       ber of code units.  The third argument  should  point  to  an  uint32_t
+       variable.  The  value  is  a  lower bound to the length of any matching
+       string. There may not be any strings of that length  that  do  actually
        match, but every string that does match is at least that long.


          PCRE2_INFO_NAMECOUNT
@@ -2170,50 +2171,50 @@
          PCRE2_INFO_NAMETABLE


        PCRE2 supports the use of named as well as numbered capturing parenthe-
-       ses.  The names are just an additional way of identifying the parenthe-
+       ses. The names are just an additional way of identifying the  parenthe-
        ses, which still acquire numbers. Several convenience functions such as
-       pcre2_substring_get_byname()  are provided for extracting captured sub-
-       strings by name. It is also possible to extract the data  directly,  by
-       first  converting  the  name to a number in order to access the correct
-       pointers in the output vector (described with pcre2_match() below).  To
-       do  the  conversion,  you  need to use the name-to-number map, which is
+       pcre2_substring_get_byname() are provided for extracting captured  sub-
+       strings  by  name. It is also possible to extract the data directly, by
+       first converting the name to a number in order to  access  the  correct
+       pointers  in the output vector (described with pcre2_match() below). To
+       do the conversion, you need to use the  name-to-number  map,  which  is
        described by these three values.


-       The map consists of a number of  fixed-size  entries.  PCRE2_INFO_NAME-
-       COUNT  gives  the number of entries, and PCRE2_INFO_NAMEENTRYSIZE gives
-       the size of each entry in code units; both of these return  a  uint32_t
+       The  map  consists  of a number of fixed-size entries. PCRE2_INFO_NAME-
+       COUNT gives the number of entries, and  PCRE2_INFO_NAMEENTRYSIZE  gives
+       the  size  of each entry in code units; both of these return a uint32_t
        value. The entry size depends on the length of the longest name.


        PCRE2_INFO_NAMETABLE returns a pointer to the first entry of the table.
-       This is a PCRE2_SPTR pointer to a block of code  units.  In  the  8-bit
-       library,  the  first two bytes of each entry are the number of the cap-
+       This  is  a  PCRE2_SPTR  pointer to a block of code units. In the 8-bit
+       library, the first two bytes of each entry are the number of  the  cap-
        turing parenthesis, most significant byte first. In the 16-bit library,
-       the  pointer  points  to 16-bit code units, the first of which contains
-       the parenthesis number. In the 32-bit library, the  pointer  points  to
-       32-bit  code units, the first of which contains the parenthesis number.
+       the pointer points to 16-bit code units, the first  of  which  contains
+       the  parenthesis  number.  In the 32-bit library, the pointer points to
+       32-bit code units, the first of which contains the parenthesis  number.
        The rest of the entry is the corresponding name, zero terminated.


-       The names are in alphabetical order. If (?| is used to create  multiple
-       groups  with  the same number, as described in the section on duplicate
-       subpattern numbers in the pcre2pattern page, the groups  may  be  given
-       the  same  name,  but  there  is only one entry in the table. Different
+       The  names are in alphabetical order. If (?| is used to create multiple
+       groups with the same number, as described in the section  on  duplicate
+       subpattern  numbers  in  the pcre2pattern page, the groups may be given
+       the same name, but there is only one  entry  in  the  table.  Different
        names for groups of the same number are not permitted.


-       Duplicate names for subpatterns with different numbers  are  permitted,
-       but  only  if  PCRE2_DUPNAMES  is  set. They appear in the table in the
-       order in which they were found in the pattern. In the  absence  of  (?|
-       this  is  the  order of increasing number; when (?| is used this is not
+       Duplicate  names  for subpatterns with different numbers are permitted,
+       but only if PCRE2_DUPNAMES is set. They appear  in  the  table  in  the
+       order  in  which  they were found in the pattern. In the absence of (?|
+       this is the order of increasing number; when (?| is used  this  is  not
        necessarily the case because later subpatterns may have lower numbers.


-       As a simple example of the name/number table,  consider  the  following
-       pattern  after  compilation by the 8-bit library (assume PCRE2_EXTENDED
+       As  a  simple  example of the name/number table, consider the following
+       pattern after compilation by the 8-bit library  (assume  PCRE2_EXTENDED
        is set, so white space - including newlines - is ignored):


          (?<date> (?<year>(\d\d)?\d\d) -
          (?<month>\d\d) - (?<day>\d\d) )


-       There are four named subpatterns, so the table has  four  entries,  and
-       each  entry  in the table is eight bytes long. The table is as follows,
+       There  are  four  named subpatterns, so the table has four entries, and
+       each entry in the table is eight bytes long. The table is  as  follows,
        with non-printing bytes shows in hexadecimal, and undefined bytes shown
        as ??:


@@ -2222,8 +2223,8 @@
          00 04 m  o  n  t  h  00
          00 02 y  e  a  r  00 ??


-       When  writing  code  to  extract  data from named subpatterns using the
-       name-to-number map, remember that the length of the entries  is  likely
+       When writing code to extract data  from  named  subpatterns  using  the
+       name-to-number  map,  remember that the length of the entries is likely
        to be different for each compiled pattern.


          PCRE2_INFO_NEWLINE
@@ -2242,14 +2243,14 @@


          PCRE2_INFO_SIZE


-       Return the size of  the  compiled  pattern  in  bytes  (for  all  three
-       libraries).  The third argument should point to a size_t variable. This
-       value includes the size of the general data  block  that  precedes  the
-       code  units of the compiled pattern itself. The value that is used when
-       pcre2_compile() is getting memory in which to place the  compiled  pat-
-       tern  may  be  slightly  larger than the value returned by this option,
-       because there are cases where the code that calculates the size has  to
-       over-estimate.  Processing  a  pattern  with  the JIT compiler does not
+       Return  the  size  of  the  compiled  pattern  in  bytes (for all three
+       libraries). The third argument should point to a size_t variable.  This
+       value  includes  the  size  of the general data block that precedes the
+       code units of the compiled pattern itself. The value that is used  when
+       pcre2_compile()  is  getting memory in which to place the compiled pat-
+       tern may be slightly larger than the value  returned  by  this  option,
+       because  there are cases where the code that calculates the size has to
+       over-estimate. Processing a pattern with  the  JIT  compiler  does  not
        alter the value returned by this option.



@@ -2260,30 +2261,30 @@
          void *user_data);


        A script language that supports the use of string arguments in callouts
-       might  like  to  scan  all the callouts in a pattern before running the
+       might like to scan all the callouts in a  pattern  before  running  the
        match. This can be done by calling pcre2_callout_enumerate(). The first
-       argument  is  a  pointer  to a compiled pattern, the second points to a
-       callback function, and the third is arbitrary user data.  The  callback
-       function  is  called  for  every callout in the pattern in the order in
+       argument is a pointer to a compiled pattern, the  second  points  to  a
+       callback  function,  and the third is arbitrary user data. The callback
+       function is called for every callout in the pattern  in  the  order  in
        which they appear. Its first argument is a pointer to a callout enumer-
-       ation  block,  and  its second argument is the user_data value that was
-       passed to pcre2_callout_enumerate(). The contents of the  callout  enu-
-       meration  block  are described in the pcre2callout documentation, which
+       ation block, and its second argument is the user_data  value  that  was
+       passed  to  pcre2_callout_enumerate(). The contents of the callout enu-
+       meration block are described in the pcre2callout  documentation,  which
        also gives further details about callouts.



SERIALIZATION AND PRECOMPILING

-       It is possible to save compiled patterns  on  disc  or  elsewhere,  and
-       reload  them  later,  subject  to a number of restrictions. The host on
-       which the patterns are reloaded must be running  the  same  version  of
+       It  is  possible  to  save  compiled patterns on disc or elsewhere, and
+       reload them later, subject to a number of  restrictions.  The  host  on
+       which  the  patterns  are  reloaded must be running the same version of
        PCRE2, with the same code unit width, and must also have the same endi-
-       anness, pointer width, and PCRE2_SIZE type.  Before  compiled  patterns
-       can  be  saved, they must be converted to a "serialized" form, which in
-       the case of PCRE2 is really just a bytecode dump.  The functions  whose
-       names  begin  with pcre2_serialize_ are used for converting to and from
-       the serialized form. They are described in the pcre2serialize  documen-
-       tation.  Note  that  PCRE2 serialization does not convert compiled pat-
+       anness,  pointer  width,  and PCRE2_SIZE type. Before compiled patterns
+       can be saved, they must be converted to a "serialized" form,  which  in
+       the  case of PCRE2 is really just a bytecode dump.  The functions whose
+       names begin with pcre2_serialize_ are used for converting to  and  from
+       the  serialized form. They are described in the pcre2serialize documen-
+       tation. Note that PCRE2 serialization does not  convert  compiled  pat-
        terns to an abstract format like Java or .NET serialization.



@@ -2297,57 +2298,57 @@

        void pcre2_match_data_free(pcre2_match_data *match_data);


-       Information about a successful or unsuccessful match  is  placed  in  a
-       match  data  block,  which  is  an opaque structure that is accessed by
-       function calls. In particular, the match data block contains  a  vector
-       of  offsets into the subject string that define the matched part of the
-       subject and any substrings that were captured. This  is  known  as  the
+       Information  about  a  successful  or unsuccessful match is placed in a
+       match data block, which is an opaque  structure  that  is  accessed  by
+       function  calls.  In particular, the match data block contains a vector
+       of offsets into the subject string that define the matched part of  the
+       subject  and  any  substrings  that were captured. This is known as the
        ovector.


-       Before  calling  pcre2_match(), pcre2_dfa_match(), or pcre2_jit_match()
+       Before calling pcre2_match(), pcre2_dfa_match(),  or  pcre2_jit_match()
        you must create a match data block by calling one of the creation func-
-       tions  above.  For pcre2_match_data_create(), the first argument is the
-       number of pairs of offsets in the  ovector.  One  pair  of  offsets  is
+       tions above. For pcre2_match_data_create(), the first argument  is  the
+       number  of  pairs  of  offsets  in  the ovector. One pair of offsets is
        required to identify the string that matched the whole pattern, with an
-       additional pair for each captured substring. For example, a value of  4
-       creates  enough space to record the matched portion of the subject plus
-       three captured substrings. A minimum of at least 1 pair is  imposed  by
+       additional  pair for each captured substring. For example, a value of 4
+       creates enough space to record the matched portion of the subject  plus
+       three  captured  substrings. A minimum of at least 1 pair is imposed by
        pcre2_match_data_create(), so it is always possible to return the over-
        all matched string.


        The second argument of pcre2_match_data_create() is a pointer to a gen-
-       eral  context, which can specify custom memory management for obtaining
+       eral context, which can specify custom memory management for  obtaining
        the memory for the match data block. If you are not using custom memory
        management, pass NULL, which causes malloc() to be used.


-       For  pcre2_match_data_create_from_pattern(),  the  first  argument is a
+       For pcre2_match_data_create_from_pattern(), the  first  argument  is  a
        pointer to a compiled pattern. The ovector is created to be exactly the
        right size to hold all the substrings a pattern might capture. The sec-
-       ond argument is again a pointer to a general context, but in this  case
+       ond  argument is again a pointer to a general context, but in this case
        if NULL is passed, the memory is obtained using the same allocator that
        was used for the compiled pattern (custom or default).


-       A match data block can be used many times, with the same  or  different
-       compiled  patterns. You can extract information from a match data block
+       A  match  data block can be used many times, with the same or different
+       compiled patterns. You can extract information from a match data  block
        after  a  match  operation  has  finished,  using  functions  that  are
-       described  in  the  sections  on  matched  strings and other match data
+       described in the sections on  matched  strings  and  other  match  data
        below.


-       When a call of pcre2_match() fails, valid  data  is  available  in  the
-       match    block    only   when   the   error   is   PCRE2_ERROR_NOMATCH,
-       PCRE2_ERROR_PARTIAL, or one of the  error  codes  for  an  invalid  UTF
+       When  a  call  of  pcre2_match()  fails, valid data is available in the
+       match   block   only   when   the   error    is    PCRE2_ERROR_NOMATCH,
+       PCRE2_ERROR_PARTIAL,  or  one  of  the  error  codes for an invalid UTF
        string. Exactly what is available depends on the error, and is detailed
        below.


-       When one of the matching functions is called, pointers to the  compiled
-       pattern  and the subject string are set in the match data block so that
-       they can be referenced by the extraction  functions.  After  running  a
-       match,  you  must not free a compiled pattern or a subject string until
-       after all operations on the match data  block  (for  that  match)  have
+       When  one of the matching functions is called, pointers to the compiled
+       pattern and the subject string are set in the match data block so  that
+       they  can  be  referenced  by the extraction functions. After running a
+       match, you must not free a compiled pattern or a subject  string  until
+       after  all  operations  on  the  match data block (for that match) have
        taken place.


-       When  a match data block itself is no longer needed, it should be freed
-       by calling pcre2_match_data_free(). If this function is called  with  a
+       When a match data block itself is no longer needed, it should be  freed
+       by  calling  pcre2_match_data_free(). If this function is called with a
        NULL argument, it returns immediately, without doing anything.



@@ -2358,15 +2359,15 @@
          uint32_t options, pcre2_match_data *match_data,
          pcre2_match_context *mcontext);


-       The  function pcre2_match() is called to match a subject string against
-       a compiled pattern, which is passed in the code argument. You can  call
+       The function pcre2_match() is called to match a subject string  against
+       a  compiled pattern, which is passed in the code argument. You can call
        pcre2_match() with the same code argument as many times as you like, in
-       order to find multiple matches in the subject string or to  match  dif-
+       order  to  find multiple matches in the subject string or to match dif-
        ferent subject strings with the same pattern.


-       This  function  is  the  main  matching facility of the library, and it
-       operates in a Perl-like manner. For specialist use  there  is  also  an
-       alternative  matching function, which is described below in the section
+       This function is the main matching facility  of  the  library,  and  it
+       operates  in  a  Perl-like  manner. For specialist use there is also an
+       alternative matching function, which is described below in the  section
        about the pcre2_dfa_match() function.


        Here is an example of a simple call to pcre2_match():
@@ -2381,7 +2382,7 @@
            md,             /* the match data block */
            NULL);          /* a match context; NULL means use defaults */


-       If the subject string is zero-terminated, the length can  be  given  as
+       If  the  subject  string is zero-terminated, the length can be given as
        PCRE2_ZERO_TERMINATED. A match context must be provided if certain less
        common matching parameters are to be changed. For details, see the sec-
        tion on the match context above.
@@ -2388,92 +2389,92 @@


    The string to be matched by pcre2_match()


-       The  subject string is passed to pcre2_match() as a pointer in subject,
-       a length in length, and a starting offset in  startoffset.  The  length
-       and  offset  are  in  code units, not characters.  That is, they are in
-       bytes for the 8-bit library, 16-bit code units for the 16-bit  library,
-       and  32-bit  code units for the 32-bit library, whether or not UTF pro-
+       The subject string is passed to pcre2_match() as a pointer in  subject,
+       a  length  in  length, and a starting offset in startoffset. The length
+       and offset are in code units, not characters.  That  is,  they  are  in
+       bytes  for the 8-bit library, 16-bit code units for the 16-bit library,
+       and 32-bit code units for the 32-bit library, whether or not  UTF  pro-
        cessing is enabled.


        If startoffset is greater than the length of the subject, pcre2_match()
-       returns  PCRE2_ERROR_BADOFFSET.  When  the starting offset is zero, the
-       search for a match starts at the beginning of the subject, and this  is
+       returns PCRE2_ERROR_BADOFFSET. When the starting offset  is  zero,  the
+       search  for a match starts at the beginning of the subject, and this is
        by far the most common case. In UTF-8 or UTF-16 mode, the starting off-
-       set must point to the start of a character, or to the end of  the  sub-
-       ject  (in  UTF-32 mode, one code unit equals one character, so all off-
-       sets are valid). Like the  pattern  string,  the  subject  may  contain
+       set  must  point to the start of a character, or to the end of the sub-
+       ject (in UTF-32 mode, one code unit equals one character, so  all  off-
+       sets  are  valid).  Like  the  pattern  string, the subject may contain
        binary zeros.


-       A  non-zero  starting offset is useful when searching for another match
-       in the same subject by calling pcre2_match()  again  after  a  previous
-       success.   Setting  startoffset  differs  from passing over a shortened
-       string and setting PCRE2_NOTBOL in the case of a  pattern  that  begins
+       A non-zero starting offset is useful when searching for  another  match
+       in  the  same  subject  by calling pcre2_match() again after a previous
+       success.  Setting startoffset differs from  passing  over  a  shortened
+       string  and  setting  PCRE2_NOTBOL in the case of a pattern that begins
        with any kind of lookbehind. For example, consider the pattern


          \Biss\B


-       which  finds  occurrences  of "iss" in the middle of words. (\B matches
-       only if the current position in the subject is not  a  word  boundary.)
+       which finds occurrences of "iss" in the middle of  words.  (\B  matches
+       only  if  the  current position in the subject is not a word boundary.)
        When applied to the string "Mississipi" the first call to pcre2_match()
-       finds the first occurrence. If pcre2_match() is called again with  just
-       the  remainder  of  the  subject,  namely  "issipi", it does not match,
+       finds  the first occurrence. If pcre2_match() is called again with just
+       the remainder of the subject,  namely  "issipi",  it  does  not  match,
        because \B is always false at the start of the subject, which is deemed
-       to  be  a word boundary. However, if pcre2_match() is passed the entire
+       to be a word boundary. However, if pcre2_match() is passed  the  entire
        string again, but with startoffset set to 4, it finds the second occur-
-       rence  of "iss" because it is able to look behind the starting point to
+       rence of "iss" because it is able to look behind the starting point  to
        discover that it is preceded by a letter.


-       Finding all the matches in a subject is tricky  when  the  pattern  can
+       Finding  all  the  matches  in a subject is tricky when the pattern can
        match an empty string. It is possible to emulate Perl's /g behaviour by
-       first  trying  the  match  again  at  the   same   offset,   with   the
-       PCRE2_NOTEMPTY_ATSTART  and  PCRE2_ANCHORED  options,  and then if that
-       fails, advancing the starting  offset  and  trying  an  ordinary  match
-       again.  There  is  some  code  that  demonstrates how to do this in the
-       pcre2demo sample program. In the most general case, you have  to  check
-       to  see  if the newline convention recognizes CRLF as a newline, and if
-       so, and the current character is CR followed by LF, advance the  start-
+       first   trying   the   match   again  at  the  same  offset,  with  the
+       PCRE2_NOTEMPTY_ATSTART and PCRE2_ANCHORED options,  and  then  if  that
+       fails,  advancing  the  starting  offset  and  trying an ordinary match
+       again. There is some code that demonstrates  how  to  do  this  in  the
+       pcre2demo  sample  program. In the most general case, you have to check
+       to see if the newline convention recognizes CRLF as a newline,  and  if
+       so,  and the current character is CR followed by LF, advance the start-
        ing offset by two characters instead of one.


        If a non-zero starting offset is passed when the pattern is anchored, a
        single attempt to match at the given offset is made. This can only suc-
-       ceed  if  the  pattern does not require the match to be at the start of
-       the subject. In other words, the anchoring must be the result  of  set-
-       ting  the PCRE2_ANCHORED option or the use of .* with PCRE2_DOTALL, not
+       ceed if the pattern does not require the match to be at  the  start  of
+       the  subject.  In other words, the anchoring must be the result of set-
+       ting the PCRE2_ANCHORED option or the use of .* with PCRE2_DOTALL,  not
        by starting the pattern with ^ or \A.


    Option bits for pcre2_match()


        The unused bits of the options argument for pcre2_match() must be zero.
-       The  only  bits  that may be set are PCRE2_ANCHORED, PCRE2_ENDANCHORED,
-       PCRE2_NOTBOL,  PCRE2_NOTEOL,  PCRE2_NOTEMPTY,   PCRE2_NOTEMPTY_ATSTART,
-       PCRE2_NO_JIT,  PCRE2_NO_UTF_CHECK,  PCRE2_PARTIAL_HARD,  and PCRE2_PAR-
+       The only bits that may be set  are  PCRE2_ANCHORED,  PCRE2_ENDANCHORED,
+       PCRE2_NOTBOL,   PCRE2_NOTEOL,  PCRE2_NOTEMPTY,  PCRE2_NOTEMPTY_ATSTART,
+       PCRE2_NO_JIT, PCRE2_NO_UTF_CHECK,  PCRE2_PARTIAL_HARD,  and  PCRE2_PAR-
        TIAL_SOFT.  Their action is described below.


-       Setting PCRE2_ANCHORED or PCRE2_ENDANCHORED at match time is  not  sup-
-       ported  by  the just-in-time (JIT) compiler. If it is set, JIT matching
-       is disabled and the interpretive code in pcre2_match()  is  run.  Apart
-       from  PCRE2_NO_JIT (obviously), the remaining options are supported for
+       Setting  PCRE2_ANCHORED  or PCRE2_ENDANCHORED at match time is not sup-
+       ported by the just-in-time (JIT) compiler. If it is set,  JIT  matching
+       is  disabled  and  the interpretive code in pcre2_match() is run. Apart
+       from PCRE2_NO_JIT (obviously), the remaining options are supported  for
        JIT matching.


          PCRE2_ANCHORED


        The PCRE2_ANCHORED option limits pcre2_match() to matching at the first
-       matching  position.  If  a pattern was compiled with PCRE2_ANCHORED, or
-       turned out to be anchored by virtue of its contents, it cannot be  made
-       unachored  at matching time. Note that setting the option at match time
+       matching position. If a pattern was compiled  with  PCRE2_ANCHORED,  or
+       turned  out to be anchored by virtue of its contents, it cannot be made
+       unachored at matching time. Note that setting the option at match  time
        disables JIT matching.


          PCRE2_ENDANCHORED


-       If the PCRE2_ENDANCHORED option is set, any string  that  pcre2_match()
-       matches  must be right at the end of the subject string. Note that set-
+       If  the  PCRE2_ENDANCHORED option is set, any string that pcre2_match()
+       matches must be right at the end of the subject string. Note that  set-
        ting the option at match time disables JIT matching.


          PCRE2_NOTBOL


        This option specifies that first character of the subject string is not
-       the  beginning  of  a  line, so the circumflex metacharacter should not
-       match before it. Setting this without  having  set  PCRE2_MULTILINE  at
+       the beginning of a line, so the  circumflex  metacharacter  should  not
+       match  before  it.  Setting  this without having set PCRE2_MULTILINE at
        compile time causes circumflex never to match. This option affects only
        the behaviour of the circumflex metacharacter. It does not affect \A.


@@ -2480,9 +2481,9 @@
          PCRE2_NOTEOL


        This option specifies that the end of the subject string is not the end
-       of  a line, so the dollar metacharacter should not match it nor (except
-       in multiline mode) a newline immediately before it. Setting this  with-
-       out  having  set PCRE2_MULTILINE at compile time causes dollar never to
+       of a line, so the dollar metacharacter should not match it nor  (except
+       in  multiline mode) a newline immediately before it. Setting this with-
+       out having set PCRE2_MULTILINE at compile time causes dollar  never  to
        match. This option affects only the behaviour of the dollar metacharac-
        ter. It does not affect \Z or \z.


@@ -2489,79 +2490,79 @@
          PCRE2_NOTEMPTY


        An empty string is not considered to be a valid match if this option is
-       set. If there are alternatives in the pattern, they are tried.  If  all
-       the  alternatives  match  the empty string, the entire match fails. For
+       set.  If  there are alternatives in the pattern, they are tried. If all
+       the alternatives match the empty string, the entire  match  fails.  For
        example, if the pattern


          a?b?


-       is applied to a string not beginning with "a" or  "b",  it  matches  an
+       is  applied  to  a  string not beginning with "a" or "b", it matches an
        empty string at the start of the subject. With PCRE2_NOTEMPTY set, this
-       match is not valid, so pcre2_match() searches further into  the  string
+       match  is  not valid, so pcre2_match() searches further into the string
        for occurrences of "a" or "b".


          PCRE2_NOTEMPTY_ATSTART


-       This  is  like PCRE2_NOTEMPTY, except that it locks out an empty string
+       This is like PCRE2_NOTEMPTY, except that it locks out an  empty  string
        match only at the first matching position, that is, at the start of the
-       subject  plus  the  starting offset. An empty string match later in the
-       subject is permitted.  If the pattern is anchored,  such  a  match  can
+       subject plus the starting offset. An empty string match  later  in  the
+       subject  is  permitted.   If  the pattern is anchored, such a match can
        occur only if the pattern contains \K.


          PCRE2_NO_JIT


-       By   default,   if   a  pattern  has  been  successfully  processed  by
-       pcre2_jit_compile(), JIT is automatically used  when  pcre2_match()  is
-       called  with  options  that JIT supports. Setting PCRE2_NO_JIT disables
+       By  default,  if  a  pattern  has  been   successfully   processed   by
+       pcre2_jit_compile(),  JIT  is  automatically used when pcre2_match() is
+       called with options that JIT supports.  Setting  PCRE2_NO_JIT  disables
        the use of JIT; it forces matching to be done by the interpreter.


          PCRE2_NO_UTF_CHECK


        When PCRE2_UTF is set at compile time, the validity of the subject as a
-       UTF  string  is  checked  by default when pcre2_match() is subsequently
-       called.  If a non-zero starting offset is given, the check  is  applied
-       only  to that part of the subject that could be inspected during match-
-       ing, and there is a check that the starting offset points to the  first
-       code  unit of a character or to the end of the subject. If there are no
-       lookbehind assertions in the pattern, the check starts at the  starting
-       offset.  Otherwise,  it  starts at the length of the longest lookbehind
+       UTF string is checked by default  when  pcre2_match()  is  subsequently
+       called.   If  a non-zero starting offset is given, the check is applied
+       only to that part of the subject that could be inspected during  match-
+       ing,  and there is a check that the starting offset points to the first
+       code unit of a character or to the end of the subject. If there are  no
+       lookbehind  assertions in the pattern, the check starts at the starting
+       offset. Otherwise, it starts at the length of  the  longest  lookbehind
        before the starting offset, or at the start of the subject if there are
-       not  that  many  characters  before  the starting offset. Note that the
+       not that many characters before the  starting  offset.  Note  that  the
        sequences \b and \B are one-character lookbehinds.


        The check is carried out before any other processing takes place, and a
-       negative  error  code is returned if the check fails. There are several
-       UTF error codes for each code unit width,  corresponding  to  different
-       problems  with  the code unit sequence. There are discussions about the
-       validity of UTF-8 strings, UTF-16 strings, and UTF-32  strings  in  the
+       negative error code is returned if the check fails. There  are  several
+       UTF  error  codes  for each code unit width, corresponding to different
+       problems with the code unit sequence. There are discussions  about  the
+       validity  of  UTF-8  strings, UTF-16 strings, and UTF-32 strings in the
        pcre2unicode page.


-       If  you  know  that  your  subject is valid, and you want to skip these
-       checks for performance reasons,  you  can  set  the  PCRE2_NO_UTF_CHECK
-       option  when  calling  pcre2_match(). You might want to do this for the
+       If you know that your subject is valid, and  you  want  to  skip  these
+       checks  for  performance  reasons,  you  can set the PCRE2_NO_UTF_CHECK
+       option when calling pcre2_match(). You might want to do  this  for  the
        second and subsequent calls to pcre2_match() if you are making repeated
        calls to find other matches in the same subject string.


-       Warning:  When  PCRE2_NO_UTF_CHECK  is  set,  the  effect of passing an
-       invalid string as a subject, or an invalid  value  of  startoffset,  is
+       Warning: When PCRE2_NO_UTF_CHECK is  set,  the  effect  of  passing  an
+       invalid  string  as  a  subject, or an invalid value of startoffset, is
        undefined.  Your program may crash or loop indefinitely.


          PCRE2_PARTIAL_HARD
          PCRE2_PARTIAL_SOFT


-       These  options  turn  on  the partial matching feature. A partial match
-       occurs if the end of the subject string is  reached  successfully,  but
-       there  are not enough subject characters to complete the match. If this
-       happens when PCRE2_PARTIAL_SOFT (but not  PCRE2_PARTIAL_HARD)  is  set,
-       matching  continues  by  testing any remaining alternatives. Only if no
-       complete match can be found is PCRE2_ERROR_PARTIAL returned instead  of
-       PCRE2_ERROR_NOMATCH.  In other words, PCRE2_PARTIAL_SOFT specifies that
-       the caller is prepared to handle a partial match, but only if  no  com-
+       These options turn on the partial matching  feature.  A  partial  match
+       occurs  if  the  end of the subject string is reached successfully, but
+       there are not enough subject characters to complete the match. If  this
+       happens  when  PCRE2_PARTIAL_SOFT  (but not PCRE2_PARTIAL_HARD) is set,
+       matching continues by testing any remaining alternatives.  Only  if  no
+       complete  match can be found is PCRE2_ERROR_PARTIAL returned instead of
+       PCRE2_ERROR_NOMATCH. In other words, PCRE2_PARTIAL_SOFT specifies  that
+       the  caller  is prepared to handle a partial match, but only if no com-
        plete match can be found.


-       If  PCRE2_PARTIAL_HARD is set, it overrides PCRE2_PARTIAL_SOFT. In this
-       case, if a partial match is found,  pcre2_match()  immediately  returns
-       PCRE2_ERROR_PARTIAL,  without  considering  any  other alternatives. In
+       If PCRE2_PARTIAL_HARD is set, it overrides PCRE2_PARTIAL_SOFT. In  this
+       case,  if  a  partial match is found, pcre2_match() immediately returns
+       PCRE2_ERROR_PARTIAL, without considering  any  other  alternatives.  In
        other words, when PCRE2_PARTIAL_HARD is set, a partial match is consid-
        ered to be more important that an alternative complete match.


@@ -2571,38 +2572,38 @@

NEWLINE HANDLING WHEN MATCHING

-       When PCRE2 is built, a default newline convention is set; this is  usu-
-       ally  the standard convention for the operating system. The default can
-       be overridden in a compile context by calling  pcre2_set_newline().  It
-       can  also be overridden by starting a pattern string with, for example,
-       (*CRLF), as described in the section  on  newline  conventions  in  the
-       pcre2pattern  page. During matching, the newline choice affects the be-
-       haviour of the dot, circumflex, and dollar metacharacters. It may  also
-       alter  the  way  the  match starting position is advanced after a match
+       When  PCRE2 is built, a default newline convention is set; this is usu-
+       ally the standard convention for the operating system. The default  can
+       be  overridden  in a compile context by calling pcre2_set_newline(). It
+       can also be overridden by starting a pattern string with, for  example,
+       (*CRLF),  as  described  in  the  section on newline conventions in the
+       pcre2pattern page. During matching, the newline choice affects the  be-
+       haviour  of the dot, circumflex, and dollar metacharacters. It may also
+       alter the way the match starting position is  advanced  after  a  match
        failure for an unanchored pattern.


        When PCRE2_NEWLINE_CRLF, PCRE2_NEWLINE_ANYCRLF, or PCRE2_NEWLINE_ANY is
-       set  as  the  newline convention, and a match attempt for an unanchored
+       set as the newline convention, and a match attempt  for  an  unanchored
        pattern fails when the current starting position is at a CRLF sequence,
-       and  the  pattern contains no explicit matches for CR or LF characters,
-       the match position is advanced by two characters  instead  of  one,  in
+       and the pattern contains no explicit matches for CR or  LF  characters,
+       the  match  position  is  advanced by two characters instead of one, in
        other words, to after the CRLF.


        The above rule is a compromise that makes the most common cases work as
-       expected. For example, if the pattern  is  .+A  (and  the  PCRE2_DOTALL
+       expected.  For  example,  if  the  pattern is .+A (and the PCRE2_DOTALL
        option is not set), it does not match the string "\r\nA" because, after
-       failing at the start, it skips both the CR and the LF before  retrying.
-       However,  the  pattern  [\r\n]A does match that string, because it con-
+       failing  at the start, it skips both the CR and the LF before retrying.
+       However, the pattern [\r\n]A does match that string,  because  it  con-
        tains an explicit CR or LF reference, and so advances only by one char-
        acter after the first failure.


        An explicit match for CR of LF is either a literal appearance of one of
-       those characters in the pattern, or one of the \r or \n  or  equivalent
+       those  characters  in the pattern, or one of the \r or \n or equivalent
        octal or hexadecimal escape sequences. Implicit matches such as [^X] do
-       not count, nor does \s, even though it includes CR and LF in the  char-
+       not  count, nor does \s, even though it includes CR and LF in the char-
        acters that it matches.


-       Notwithstanding  the above, anomalous effects may still occur when CRLF
+       Notwithstanding the above, anomalous effects may still occur when  CRLF
        is a valid newline sequence and explicit \r or \n escapes appear in the
        pattern.


@@ -2613,81 +2614,81 @@

        PCRE2_SIZE *pcre2_get_ovector_pointer(pcre2_match_data *match_data);


-       In  general, a pattern matches a certain portion of the subject, and in
-       addition, further substrings from the subject  may  be  picked  out  by
-       parenthesized  parts  of  the  pattern.  Following the usage in Jeffrey
-       Friedl's book, this is called "capturing"  in  what  follows,  and  the
-       phrase  "capturing subpattern" or "capturing group" is used for a frag-
-       ment of a pattern that picks out a substring.  PCRE2  supports  several
+       In general, a pattern matches a certain portion of the subject, and  in
+       addition,  further  substrings  from  the  subject may be picked out by
+       parenthesized parts of the pattern.  Following  the  usage  in  Jeffrey
+       Friedl's  book,  this  is  called  "capturing" in what follows, and the
+       phrase "capturing subpattern" or "capturing group" is used for a  frag-
+       ment  of  a  pattern that picks out a substring. PCRE2 supports several
        other kinds of parenthesized subpattern that do not cause substrings to
-       be captured. The pcre2_pattern_info() function can be used to find  out
+       be  captured. The pcre2_pattern_info() function can be used to find out
        how many capturing subpatterns there are in a compiled pattern.


-       You  can  use  auxiliary functions for accessing captured substrings by
+       You can use auxiliary functions for accessing  captured  substrings  by
        number or by name, as described in sections below.


        Alternatively, you can make direct use of the vector of PCRE2_SIZE val-
-       ues,  called  the  ovector,  which  contains  the  offsets  of captured
-       strings.  It  is  part  of  the  match  data   block.    The   function
-       pcre2_get_ovector_pointer()  returns  the  address  of the ovector, and
+       ues, called  the  ovector,  which  contains  the  offsets  of  captured
+       strings.   It   is   part  of  the  match  data  block.   The  function
+       pcre2_get_ovector_pointer() returns the address  of  the  ovector,  and
        pcre2_get_ovector_count() returns the number of pairs of values it con-
        tains.


        Within the ovector, the first in each pair of values is set to the off-
        set of the first code unit of a substring, and the second is set to the
-       offset  of the first code unit after the end of a substring. These val-
-       ues are always code unit offsets, not character offsets. That is,  they
-       are  byte  offsets  in  the 8-bit library, 16-bit offsets in the 16-bit
+       offset of the first code unit after the end of a substring. These  val-
+       ues  are always code unit offsets, not character offsets. That is, they
+       are byte offsets in the 8-bit library, 16-bit  offsets  in  the  16-bit
        library, and 32-bit offsets in the 32-bit library.


-       After a partial match  (error  return  PCRE2_ERROR_PARTIAL),  only  the
-       first  pair  of  offsets  (that is, ovector[0] and ovector[1]) are set.
-       They identify the part of the subject that was partially  matched.  See
+       After  a  partial  match  (error  return PCRE2_ERROR_PARTIAL), only the
+       first pair of offsets (that is, ovector[0]  and  ovector[1])  are  set.
+       They  identify  the part of the subject that was partially matched. See
        the pcre2partial documentation for details of partial matching.


-       After  a  fully  successful match, the first pair of offsets identifies
-       the portion of the subject string that was matched by the  entire  pat-
-       tern.  The  next  pair is used for the first captured substring, and so
-       on. The value returned by pcre2_match() is one more  than  the  highest
-       numbered  pair  that  has been set. For example, if two substrings have
-       been captured, the returned value is 3. If there are no  captured  sub-
+       After a fully successful match, the first pair  of  offsets  identifies
+       the  portion  of the subject string that was matched by the entire pat-
+       tern. The next pair is used for the first captured  substring,  and  so
+       on.  The  value  returned by pcre2_match() is one more than the highest
+       numbered pair that has been set. For example, if  two  substrings  have
+       been  captured,  the returned value is 3. If there are no captured sub-
        strings, the return value from a successful match is 1, indicating that
        just the first pair of offsets has been set.


-       If a pattern uses the \K escape sequence within a  positive  assertion,
+       If  a  pattern uses the \K escape sequence within a positive assertion,
        the reported start of a successful match can be greater than the end of
-       the match.  For example, if the pattern  (?=ab\K)  is  matched  against
+       the  match.   For  example,  if the pattern (?=ab\K) is matched against
        "ab", the start and end offset values for the match are 2 and 0.


-       If  a  capturing subpattern group is matched repeatedly within a single
-       match operation, it is the last portion of the subject that it  matched
+       If a capturing subpattern group is matched repeatedly within  a  single
+       match  operation, it is the last portion of the subject that it matched
        that is returned.


        If the ovector is too small to hold all the captured substring offsets,
-       as much as possible is filled in, and the function returns a  value  of
-       zero.  If captured substrings are not of interest, pcre2_match() may be
+       as  much  as possible is filled in, and the function returns a value of
+       zero. If captured substrings are not of interest, pcre2_match() may  be
        called with a match data block whose ovector is of minimum length (that
        is, one pair).


-       It  is  possible for capturing subpattern number n+1 to match some part
+       It is possible for capturing subpattern number n+1 to match  some  part
        of the subject when subpattern n has not been used at all. For example,
-       if  the  string  "abc"  is  matched against the pattern (a|(z))(bc) the
+       if the string "abc" is matched  against  the  pattern  (a|(z))(bc)  the
        return from the function is 4, and subpatterns 1 and 3 are matched, but
-       2  is  not.  When  this happens, both values in the offset pairs corre-
+       2 is not. When this happens, both values in  the  offset  pairs  corre-
        sponding to unused subpatterns are set to PCRE2_UNSET.


-       Offset values that correspond to unused subpatterns at the end  of  the
-       expression  are  also  set  to  PCRE2_UNSET. For example, if the string
+       Offset  values  that correspond to unused subpatterns at the end of the
+       expression are also set to PCRE2_UNSET.  For  example,  if  the  string
        "abc" is matched against the pattern (abc)(x(yz)?)? subpatterns 2 and 3
-       are  not matched.  The return from the function is 2, because the high-
+       are not matched.  The return from the function is 2, because the  high-
        est used capturing subpattern number is 1. The offsets for for the sec-
-       ond  and  third  capturing  subpatterns  (assuming  the vector is large
+       ond and third capturing  subpatterns  (assuming  the  vector  is  large
        enough, of course) are set to PCRE2_UNSET.


        Elements in the ovector that do not correspond to capturing parentheses
        in the pattern are never changed. That is, if a pattern contains n cap-
        turing parentheses, no more than ovector[0] to ovector[2n+1] are set by
-       pcre2_match().  The  other  elements retain whatever values they previ-
+       pcre2_match(). The other elements retain whatever  values  they  previ-
        ously had.



@@ -2697,55 +2698,55 @@

        PCRE2_SIZE pcre2_get_startchar(pcre2_match_data *match_data);


-       As well as the offsets in the ovector, other information about a  match
-       is  retained  in the match data block and can be retrieved by the above
-       functions in appropriate circumstances. If they  are  called  at  other
+       As  well as the offsets in the ovector, other information about a match
+       is retained in the match data block and can be retrieved by  the  above
+       functions  in  appropriate  circumstances.  If they are called at other
        times, the result is undefined.


-       After  a  successful match, a partial match (PCRE2_ERROR_PARTIAL), or a
+       After a successful match, a partial match (PCRE2_ERROR_PARTIAL),  or  a
        failure to match (PCRE2_ERROR_NOMATCH), a (*MARK), (*PRUNE), or (*THEN)
-       name  may  be available. The function pcre2_get_mark() can be called to
-       access this name. The same function applies  to  all  three  verbs.  It
+       name may be available. The function pcre2_get_mark() can be  called  to
+       access  this  name.  The  same  function applies to all three verbs. It
        returns a pointer to the zero-terminated name, which is within the com-
        piled pattern. If no name is available, NULL is returned. The length of
-       the  name  (excluding  the terminating zero) is stored in the code unit
-       that precedes the name. You should use this length instead  of  relying
+       the name (excluding the terminating zero) is stored in  the  code  unit
+       that  precedes  the name. You should use this length instead of relying
        on the terminating zero if the name might contain a binary zero.


-       After  a  successful  match,  the  name  that  is  returned is the last
-       (*MARK), (*PRUNE), or (*THEN) name encountered  on  the  matching  path
-       through  the  pattern.  Instances of (*PRUNE) and (*THEN) without names
-       are  ignored.  Thus,  for  example,  if  the  matching  path   contains
-       (*MARK:A)(*PRUNE),  the  name "A" is returned.  After a "no match" or a
-       partial match, the last encountered name  is  returned.   For  example,
+       After a successful match,  the  name  that  is  returned  is  the  last
+       (*MARK),  (*PRUNE),  or  (*THEN)  name encountered on the matching path
+       through the pattern.  Instances of (*PRUNE) and (*THEN)  without  names
+       are   ignored.  Thus,  for  example,  if  the  matching  path  contains
+       (*MARK:A)(*PRUNE), the name "A" is returned.  After a "no match"  or  a
+       partial  match,  the  last  encountered name is returned.  For example,
        consider this pattern:


          ^(*MARK:A)((*MARK:B)a|b)c


-       When  it  matches "bc", the returned name is A. The B mark is "seen" in
-       the first branch of the group, but it is not on the matching  path.  On
-       the  other  hand,  when  this pattern fails to match "bx", the returned
+       When it matches "bc", the returned name is A. The B mark is  "seen"  in
+       the  first  branch of the group, but it is not on the matching path. On
+       the other hand, when this pattern fails to  match  "bx",  the  returned
        name is B.


-       Warning: By default, certain start-of-match optimizations are  used  to
-       give  a  fast "no match" result in some situations. For example, if the
-       anchoring is removed from the pattern above, there is an initial  check
-       for  the  presence  of  "c"  in the subject before running the matching
+       Warning:  By  default, certain start-of-match optimizations are used to
+       give a fast "no match" result in some situations. For example,  if  the
+       anchoring  is removed from the pattern above, there is an initial check
+       for the presence of "c" in the  subject  before  running  the  matching
        engine. This check fails for "bx", causing a match failure without see-
        ing any marks. You can disable the start-of-match optimizations by set-
        ting the PCRE2_NO_START_OPTIMIZE option for pcre2_compile() or starting
        the pattern with (*NO_START_OPT).


-       After  a  successful  match, a partial match, or one of the invalid UTF
-       errors (for example, PCRE2_ERROR_UTF8_ERR5), pcre2_get_startchar()  can
+       After a successful match, a partial match, or one of  the  invalid  UTF
+       errors  (for example, PCRE2_ERROR_UTF8_ERR5), pcre2_get_startchar() can
        be called. After a successful or partial match it returns the code unit
-       offset of the character at which the match started. For  a  non-partial
-       match,  this can be different to the value of ovector[0] if the pattern
-       contains the \K escape sequence. After a partial match,  however,  this
-       value  is  always the same as ovector[0] because \K does not affect the
+       offset  of  the character at which the match started. For a non-partial
+       match, this can be different to the value of ovector[0] if the  pattern
+       contains  the  \K escape sequence. After a partial match, however, this
+       value is always the same as ovector[0] because \K does not  affect  the
        result of a partial match.


-       After a UTF check failure, pcre2_get_startchar() can be used to  obtain
+       After  a UTF check failure, pcre2_get_startchar() can be used to obtain
        the code unit offset of the invalid UTF character. Details are given in
        the pcre2unicode page.


@@ -2752,14 +2753,14 @@

ERROR RETURNS FROM pcre2_match()

-       If pcre2_match() fails, it returns a negative number. This can be  con-
-       verted  to a text string by calling the pcre2_get_error_message() func-
-       tion (see "Obtaining a textual error message" below).   Negative  error
-       codes  are  also  returned  by other functions, and are documented with
-       them. The codes are given names in the header file. If UTF checking  is
+       If  pcre2_match() fails, it returns a negative number. This can be con-
+       verted to a text string by calling the pcre2_get_error_message()  func-
+       tion  (see  "Obtaining a textual error message" below).  Negative error
+       codes are also returned by other functions,  and  are  documented  with
+       them.  The codes are given names in the header file. If UTF checking is
        in force and an invalid UTF subject string is detected, one of a number
-       of UTF-specific negative error codes is returned. Details are given  in
-       the  pcre2unicode  page. The following are the other errors that may be
+       of  UTF-specific negative error codes is returned. Details are given in
+       the pcre2unicode page. The following are the other errors that  may  be
        returned by pcre2_match():


          PCRE2_ERROR_NOMATCH
@@ -2768,20 +2769,20 @@


          PCRE2_ERROR_PARTIAL


-       The subject string did not match, but it did match partially.  See  the
+       The  subject  string did not match, but it did match partially. See the
        pcre2partial documentation for details of partial matching.


          PCRE2_ERROR_BADMAGIC


        PCRE2 stores a 4-byte "magic number" at the start of the compiled code,
-       to catch the case when it is passed a junk pointer. This is  the  error
+       to  catch  the case when it is passed a junk pointer. This is the error
        that is returned when the magic number is not present.


          PCRE2_ERROR_BADMODE


-       This  error is given when a compiled pattern is passed to a function in
-       a library of a different code unit width, for example, a  pattern  com-
-       piled  by  the  8-bit  library  is passed to a 16-bit or 32-bit library
+       This error is given when a compiled pattern is passed to a function  in
+       a  library  of a different code unit width, for example, a pattern com-
+       piled by the 8-bit library is passed to  a  16-bit  or  32-bit  library
        function.


          PCRE2_ERROR_BADOFFSET
@@ -2795,15 +2796,15 @@
          PCRE2_ERROR_BADUTFOFFSET


        The UTF code unit sequence that was passed as a subject was checked and
-       found  to be valid (the PCRE2_NO_UTF_CHECK option was not set), but the
-       value of startoffset did not point to the beginning of a UTF  character
+       found to be valid (the PCRE2_NO_UTF_CHECK option was not set), but  the
+       value  of startoffset did not point to the beginning of a UTF character
        or the end of the subject.


          PCRE2_ERROR_CALLOUT


-       This  error  is never generated by pcre2_match() itself. It is provided
-       for use by callout  functions  that  want  to  cause  pcre2_match()  or
-       pcre2_callout_enumerate()  to  return a distinctive error code. See the
+       This error is never generated by pcre2_match() itself. It  is  provided
+       for  use  by  callout  functions  that  want  to cause pcre2_match() or
+       pcre2_callout_enumerate() to return a distinctive error code.  See  the
        pcre2callout documentation for details.


          PCRE2_ERROR_DEPTHLIMIT
@@ -2816,14 +2817,14 @@


          PCRE2_ERROR_INTERNAL


-       An unexpected internal error has occurred. This error could  be  caused
+       An  unexpected  internal error has occurred. This error could be caused
        by a bug in PCRE2 or by overwriting of the compiled pattern.


          PCRE2_ERROR_JIT_STACKLIMIT


-       This  error  is  returned  when a pattern that was successfully studied
-       using JIT is being matched, but the memory available for  the  just-in-
-       time  processing stack is not large enough. See the pcre2jit documenta-
+       This error is returned when a pattern  that  was  successfully  studied
+       using  JIT  is being matched, but the memory available for the just-in-
+       time processing stack is not large enough. See the pcre2jit  documenta-
        tion for more details.


          PCRE2_ERROR_MATCHLIMIT
@@ -2832,10 +2833,10 @@


          PCRE2_ERROR_NOMEMORY


-       If a pattern contains many nested backtracking points, heap  memory  is
-       used  to  remember them. This error is given when the memory allocation
-       function (default or  custom)  fails.  Note  that  a  different  error,
-       PCRE2_ERROR_HEAPLIMIT,  is given if the amount of memory needed exceeds
+       If  a  pattern contains many nested backtracking points, heap memory is
+       used to remember them. This error is given when the  memory  allocation
+       function  (default  or  custom)  fails.  Note  that  a different error,
+       PCRE2_ERROR_HEAPLIMIT, is given if the amount of memory needed  exceeds
        the heap limit.


          PCRE2_ERROR_NULL
@@ -2844,12 +2845,12 @@


          PCRE2_ERROR_RECURSELOOP


-       This error is returned when  pcre2_match()  detects  a  recursion  loop
-       within  the  pattern. Specifically, it means that either the whole pat-
+       This  error  is  returned  when  pcre2_match() detects a recursion loop
+       within the pattern. Specifically, it means that either the  whole  pat-
        tern or a subpattern has been called recursively for the second time at
-       the  same  position  in  the  subject string. Some simple patterns that
-       might do this are detected and faulted at compile time, but  more  com-
-       plicated  cases,  in particular mutual recursions between two different
+       the same position in the subject  string.  Some  simple  patterns  that
+       might  do  this are detected and faulted at compile time, but more com-
+       plicated cases, in particular mutual recursions between  two  different
        subpatterns, cannot be detected until matching is attempted.



@@ -2858,20 +2859,20 @@
        int pcre2_get_error_message(int errorcode, PCRE2_UCHAR *buffer,
          PCRE2_SIZE bufflen);


-       A text message for an error code  from  any  PCRE2  function  (compile,
-       match,  or  auxiliary)  can be obtained by calling pcre2_get_error_mes-
-       sage(). The code is passed as the first argument,  with  the  remaining
-       two  arguments  specifying  a  code  unit buffer and its length in code
-       units, into which the text message is placed. The message  is  returned
-       in  code  units  of the appropriate width for the library that is being
+       A  text  message  for  an  error code from any PCRE2 function (compile,
+       match, or auxiliary) can be obtained  by  calling  pcre2_get_error_mes-
+       sage().  The  code  is passed as the first argument, with the remaining
+       two arguments specifying a code unit buffer  and  its  length  in  code
+       units,  into  which the text message is placed. The message is returned
+       in code units of the appropriate width for the library  that  is  being
        used.


-       The returned message is terminated with a trailing zero, and the  func-
-       tion  returns  the  number  of  code units used, excluding the trailing
+       The  returned message is terminated with a trailing zero, and the func-
+       tion returns the number of code  units  used,  excluding  the  trailing
        zero.  If  the  error  number  is  unknown,  the  negative  error  code
-       PCRE2_ERROR_BADDATA  is  returned. If the buffer is too small, the mes-
-       sage is truncated (but still with a trailing zero),  and  the  negative
-       error  code PCRE2_ERROR_NOMEMORY is returned.  None of the messages are
+       PCRE2_ERROR_BADDATA is returned. If the buffer is too small,  the  mes-
+       sage  is  truncated  (but still with a trailing zero), and the negative
+       error code PCRE2_ERROR_NOMEMORY is returned.  None of the messages  are
        very long; a buffer size of 120 code units is ample.



@@ -2890,39 +2891,39 @@

        void pcre2_substring_free(PCRE2_UCHAR *buffer);


-       Captured substrings can be accessed directly by using  the  ovector  as
+       Captured  substrings  can  be accessed directly by using the ovector as
        described above.  For convenience, auxiliary functions are provided for
-       extracting  captured  substrings  as  new,  separate,   zero-terminated
+       extracting   captured  substrings  as  new,  separate,  zero-terminated
        strings. A substring that contains a binary zero is correctly extracted
-       and has a further zero added on the end, but  the  result  is  not,  of
+       and  has  a  further  zero  added on the end, but the result is not, of
        course, a C string.


        The functions in this section identify substrings by number. The number
        zero refers to the entire matched substring, with higher numbers refer-
-       ring  to  substrings  captured by parenthesized groups. After a partial
-       match, only substring zero is available.  An  attempt  to  extract  any
-       other  substring  gives the error PCRE2_ERROR_PARTIAL. The next section
+       ring to substrings captured by parenthesized groups.  After  a  partial
+       match,  only  substring  zero  is  available. An attempt to extract any
+       other substring gives the error PCRE2_ERROR_PARTIAL. The  next  section
        describes similar functions for extracting captured substrings by name.


-       If a pattern uses the \K escape sequence within a  positive  assertion,
+       If  a  pattern uses the \K escape sequence within a positive assertion,
        the reported start of a successful match can be greater than the end of
-       the match.  For example, if the pattern  (?=ab\K)  is  matched  against
-       "ab",  the  start  and  end offset values for the match are 2 and 0. In
-       this situation, calling these functions with a  zero  substring  number
+       the  match.   For  example,  if the pattern (?=ab\K) is matched against
+       "ab", the start and end offset values for the match are  2  and  0.  In
+       this  situation,  calling  these functions with a zero substring number
        extracts a zero-length empty string.


-       You  can  find the length in code units of a captured substring without
-       extracting it by calling pcre2_substring_length_bynumber().  The  first
-       argument  is a pointer to the match data block, the second is the group
-       number, and the third is a pointer to a variable into which the  length
-       is  placed.  If  you just want to know whether or not the substring has
+       You can find the length in code units of a captured  substring  without
+       extracting  it  by calling pcre2_substring_length_bynumber(). The first
+       argument is a pointer to the match data block, the second is the  group
+       number,  and the third is a pointer to a variable into which the length
+       is placed. If you just want to know whether or not  the  substring  has
        been captured, you can pass the third argument as NULL.


-       The pcre2_substring_copy_bynumber() function  copies  a  captured  sub-
-       string  into  a supplied buffer, whereas pcre2_substring_get_bynumber()
-       copies it into new memory, obtained using the  same  memory  allocation
-       function  that  was  used for the match data block. The first two argu-
-       ments of these functions are a pointer to the match data  block  and  a
+       The  pcre2_substring_copy_bynumber()  function  copies  a captured sub-
+       string into a supplied buffer,  whereas  pcre2_substring_get_bynumber()
+       copies  it  into  new memory, obtained using the same memory allocation
+       function that was used for the match data block. The  first  two  argu-
+       ments  of  these  functions are a pointer to the match data block and a
        capturing group number.


        The final arguments of pcre2_substring_copy_bynumber() are a pointer to
@@ -2931,25 +2932,25 @@
        for the extracted substring, excluding the terminating zero.


        For pcre2_substring_get_bynumber() the third and fourth arguments point
-       to  variables that are updated with a pointer to the new memory and the
-       number of code units that comprise the substring, again  excluding  the
-       terminating  zero.  When  the substring is no longer needed, the memory
+       to variables that are updated with a pointer to the new memory and  the
+       number  of  code units that comprise the substring, again excluding the
+       terminating zero. When the substring is no longer  needed,  the  memory
        should be freed by calling pcre2_substring_free().


-       The return value from all these functions is zero  for  success,  or  a
-       negative  error  code.  If  the pattern match failed, the match failure
-       code is returned.  If a substring number  greater  than  zero  is  used
-       after  a partial match, PCRE2_ERROR_PARTIAL is returned. Other possible
+       The  return  value  from  all these functions is zero for success, or a
+       negative error code. If the pattern match  failed,  the  match  failure
+       code  is  returned.   If  a  substring number greater than zero is used
+       after a partial match, PCRE2_ERROR_PARTIAL is returned. Other  possible
        error codes are:


          PCRE2_ERROR_NOMEMORY


-       The buffer was too small for  pcre2_substring_copy_bynumber(),  or  the
+       The  buffer  was  too small for pcre2_substring_copy_bynumber(), or the
        attempt to get memory failed for pcre2_substring_get_bynumber().


          PCRE2_ERROR_NOSUBSTRING


-       There  is  no  substring  with that number in the pattern, that is, the
+       There is no substring with that number in the  pattern,  that  is,  the
        number is greater than the number of capturing parentheses.


          PCRE2_ERROR_UNAVAILABLE
@@ -2960,8 +2961,8 @@


          PCRE2_ERROR_UNSET


-       The substring did not participate in the match.  For  example,  if  the
-       pattern  is  (abc)|(def) and the subject is "def", and the ovector con-
+       The  substring  did  not  participate in the match. For example, if the
+       pattern is (abc)|(def) and the subject is "def", and the  ovector  con-
        tains at least two capturing slots, substring number 1 is unset.



@@ -2972,32 +2973,32 @@

        void pcre2_substring_list_free(PCRE2_SPTR *list);


-       The pcre2_substring_list_get() function  extracts  all  available  sub-
-       strings  and  builds  a  list of pointers to them. It also (optionally)
-       builds a second list that  contains  their  lengths  (in  code  units),
+       The  pcre2_substring_list_get()  function  extracts  all available sub-
+       strings and builds a list of pointers to  them.  It  also  (optionally)
+       builds  a  second  list  that  contains  their lengths (in code units),
        excluding a terminating zero that is added to each of them. All this is
        done in a single block of memory that is obtained using the same memory
        allocation function that was used to get the match data block.


-       This  function  must be called only after a successful match. If called
+       This function must be called only after a successful match.  If  called
        after a partial match, the error code PCRE2_ERROR_PARTIAL is returned.


-       The address of the memory block is returned via listptr, which is  also
+       The  address of the memory block is returned via listptr, which is also
        the start of the list of string pointers. The end of the list is marked
-       by a NULL pointer. The address of the list of lengths is  returned  via
-       lengthsptr.  If your strings do not contain binary zeros and you do not
+       by  a  NULL pointer. The address of the list of lengths is returned via
+       lengthsptr. If your strings do not contain binary zeros and you do  not
        therefore need the lengths, you may supply NULL as the lengthsptr argu-
-       ment  to  disable  the  creation of a list of lengths. The yield of the
-       function is zero if all went well, or PCRE2_ERROR_NOMEMORY if the  mem-
-       ory  block could not be obtained. When the list is no longer needed, it
+       ment to disable the creation of a list of lengths.  The  yield  of  the
+       function  is zero if all went well, or PCRE2_ERROR_NOMEMORY if the mem-
+       ory block could not be obtained. When the list is no longer needed,  it
        should be freed by calling pcre2_substring_list_free().


        If this function encounters a substring that is unset, which can happen
-       when  capturing subpattern number n+1 matches some part of the subject,
-       but subpattern n has not been used at all, it returns an empty  string.
-       This  can  be  distinguished  from  a  genuine zero-length substring by
+       when capturing subpattern number n+1 matches some part of the  subject,
+       but  subpattern n has not been used at all, it returns an empty string.
+       This can be distinguished  from  a  genuine  zero-length  substring  by
        inspecting  the  appropriate  offset  in  the  ovector,  which  contain
-       PCRE2_UNSET   for   unset   substrings,   or   by   calling  pcre2_sub-
+       PCRE2_UNSET  for   unset   substrings,   or   by   calling   pcre2_sub-
        string_length_bynumber().



@@ -3017,39 +3018,39 @@

        void pcre2_substring_free(PCRE2_UCHAR *buffer);


-       To extract a substring by name, you first have to find associated  num-
+       To  extract a substring by name, you first have to find associated num-
        ber.  For example, for this pattern:


          (a+)b(?<xxx>\d+)...


        the number of the subpattern called "xxx" is 2. If the name is known to
-       be unique (PCRE2_DUPNAMES was not set), you can find  the  number  from
+       be  unique  (PCRE2_DUPNAMES  was not set), you can find the number from
        the name by calling pcre2_substring_number_from_name(). The first argu-
-       ment is the compiled pattern, and the second is the name. The yield  of
+       ment  is the compiled pattern, and the second is the name. The yield of
        the function is the subpattern number, PCRE2_ERROR_NOSUBSTRING if there
-       is no subpattern of  that  name,  or  PCRE2_ERROR_NOUNIQUESUBSTRING  if
-       there  is  more than one subpattern of that name. Given the number, you
-       can extract the substring directly from the ovector, or use one of  the
+       is  no  subpattern  of  that  name, or PCRE2_ERROR_NOUNIQUESUBSTRING if
+       there is more than one subpattern of that name. Given the  number,  you
+       can  extract the substring directly from the ovector, or use one of the
        "bynumber" functions described above.


-       For  convenience,  there are also "byname" functions that correspond to
-       the "bynumber" functions, the only difference  being  that  the  second
-       argument  is  a  name instead of a number. If PCRE2_DUPNAMES is set and
+       For convenience, there are also "byname" functions that  correspond  to
+       the  "bynumber"  functions,  the  only difference being that the second
+       argument is a name instead of a number. If PCRE2_DUPNAMES  is  set  and
        there are duplicate names, these functions scan all the groups with the
        given name, and return the first named string that is set.


-       If  there are no groups with the given name, PCRE2_ERROR_NOSUBSTRING is
-       returned. If all groups with the name have  numbers  that  are  greater
-       than  the  number  of  slots in the ovector, PCRE2_ERROR_UNAVAILABLE is
-       returned. If there is at least one group with a slot  in  the  ovector,
+       If there are no groups with the given name, PCRE2_ERROR_NOSUBSTRING  is
+       returned.  If  all  groups  with the name have numbers that are greater
+       than the number of slots in  the  ovector,  PCRE2_ERROR_UNAVAILABLE  is
+       returned.  If  there  is at least one group with a slot in the ovector,
        but no group is found to be set, PCRE2_ERROR_UNSET is returned.


        Warning: If the pattern uses the (?| feature to set up multiple subpat-
-       terns with the same number, as described in the  section  on  duplicate
-       subpattern  numbers  in  the pcre2pattern page, you cannot use names to
-       distinguish the different subpatterns, because names are  not  included
-       in  the compiled code. The matching process uses only numbers. For this
-       reason, the use of different names for subpatterns of the  same  number
+       terns  with  the  same number, as described in the section on duplicate
+       subpattern numbers in the pcre2pattern page, you cannot  use  names  to
+       distinguish  the  different subpatterns, because names are not included
+       in the compiled code. The matching process uses only numbers. For  this
+       reason,  the  use of different names for subpatterns of the same number
        causes an error at compile time.



@@ -3062,45 +3063,45 @@
          PCRE2_SIZE rlength, PCRE2_UCHAR *outputbufferP,
          PCRE2_SIZE *outlengthptr);


-       This  function calls pcre2_match() and then makes a copy of the subject
-       string in outputbuffer, replacing the part that was  matched  with  the
-       replacement  string,  whose  length is supplied in rlength. This can be
+       This function calls pcre2_match() and then makes a copy of the  subject
+       string  in  outputbuffer,  replacing the part that was matched with the
+       replacement string, whose length is supplied in rlength.  This  can  be
        given as PCRE2_ZERO_TERMINATED for a zero-terminated string. Matches in
-       which  a  \K item in a lookahead in the pattern causes the match to end
-       before it starts are not supported, and give rise to an  error  return.
+       which a \K item in a lookahead in the pattern causes the match  to  end
+       before  it  starts are not supported, and give rise to an error return.
        For global replacements, matches in which \K in a lookbehind causes the
-       match to start earlier than the point that was reached in the  previous
+       match  to start earlier than the point that was reached in the previous
        iteration are also not supported.


-       The  first  seven  arguments  of pcre2_substitute() are the same as for
+       The first seven arguments of pcre2_substitute() are  the  same  as  for
        pcre2_match(), except that the partial matching options are not permit-
-       ted,  and  match_data may be passed as NULL, in which case a match data
-       block is obtained and freed within this function, using memory  manage-
-       ment  functions from the match context, if provided, or else those that
+       ted, and match_data may be passed as NULL, in which case a  match  data
+       block  is obtained and freed within this function, using memory manage-
+       ment functions from the match context, if provided, or else those  that
        were used to allocate memory for the compiled code.


-       The outlengthptr argument must point to a variable  that  contains  the
-       length,  in  code  units, of the output buffer. If the function is suc-
-       cessful, the value is updated to contain the length of the new  string,
+       The  outlengthptr  argument  must point to a variable that contains the
+       length, in code units, of the output buffer. If the  function  is  suc-
+       cessful,  the value is updated to contain the length of the new string,
        excluding the trailing zero that is automatically added.


-       If  the  function  is  not  successful,  the value set via outlengthptr
-       depends on the type of error. For  syntax  errors  in  the  replacement
-       string,  the  value  is  the offset in the replacement string where the
-       error was detected. For other  errors,  the  value  is  PCRE2_UNSET  by
-       default.  This  includes the case of the output buffer being too small,
-       unless PCRE2_SUBSTITUTE_OVERFLOW_LENGTH is set (see  below),  in  which
-       case  the  value  is the minimum length needed, including space for the
-       trailing zero. Note that in  order  to  compute  the  required  length,
-       pcre2_substitute()  has  to  simulate  all  the  matching  and copying,
+       If the function is not  successful,  the  value  set  via  outlengthptr
+       depends  on  the  type  of  error. For syntax errors in the replacement
+       string, the value is the offset in the  replacement  string  where  the
+       error  was  detected.  For  other  errors,  the value is PCRE2_UNSET by
+       default. This includes the case of the output buffer being  too  small,
+       unless  PCRE2_SUBSTITUTE_OVERFLOW_LENGTH  is  set (see below), in which
+       case the value is the minimum length needed, including  space  for  the
+       trailing  zero.  Note  that  in  order  to compute the required length,
+       pcre2_substitute() has  to  simulate  all  the  matching  and  copying,
        instead of giving an error return as soon as the buffer overflows. Note
        also that the length is in code units, not bytes.


-       In  the replacement string, which is interpreted as a UTF string in UTF
-       mode, and is checked for UTF  validity  unless  the  PCRE2_NO_UTF_CHECK
+       In the replacement string, which is interpreted as a UTF string in  UTF
+       mode,  and  is  checked  for UTF validity unless the PCRE2_NO_UTF_CHECK
        option is set, a dollar character is an escape character that can spec-
-       ify the insertion of  characters  from  capturing  groups  or  (*MARK),
-       (*PRUNE),  or  (*THEN)  items  in  the pattern. The following forms are
+       ify  the  insertion  of  characters  from  capturing groups or (*MARK),
+       (*PRUNE), or (*THEN) items in the  pattern.  The  following  forms  are
        always recognized:


          $$                  insert a dollar character
@@ -3107,19 +3108,19 @@
          $<n> or ${<n>}      insert the contents of group <n>
          $*MARK or ${*MARK}  insert a (*MARK), (*PRUNE), or (*THEN) name


-       Either a group number or a group name  can  be  given  for  <n>.  Curly
-       brackets  are  required only if the following character would be inter-
+       Either  a  group  number  or  a  group name can be given for <n>. Curly
+       brackets are required only if the following character would  be  inter-
        preted as part of the number or name. The number may be zero to include
-       the  entire  matched  string.   For  example,  if  the pattern a(b)c is
-       matched with "=abc=" and the replacement string "+$1$0$1+", the  result
+       the entire matched string.   For  example,  if  the  pattern  a(b)c  is
+       matched  with "=abc=" and the replacement string "+$1$0$1+", the result
        is "=+babcb+=".


        $*MARK inserts the name from the last encountered (*MARK), (*PRUNE), or
-       (*THEN) on the matching path that  has  a  name.  (*MARK)  must  always
-       include  a name, but (*PRUNE) and (*THEN) need not. For example, in the
-       case  of  (*MARK:A)(*PRUNE)  the  name  inserted  is   "A",   but   for
-       (*MARK:A)(*PRUNE:B)  the  relevant  name  is "B".  This facility can be
-       used to perform simple simultaneous substitutions,  as  this  pcre2test
+       (*THEN)  on  the  matching  path  that  has a name. (*MARK) must always
+       include a name, but (*PRUNE) and (*THEN) need not. For example, in  the
+       case   of   (*MARK:A)(*PRUNE)   the  name  inserted  is  "A",  but  for
+       (*MARK:A)(*PRUNE:B) the relevant name is "B".   This  facility  can  be
+       used  to  perform  simple simultaneous substitutions, as this pcre2test
        example shows:


          /(*MARK:pear)apple|(*MARK:orange)lemon/g,replace=${*MARK}
@@ -3126,19 +3127,19 @@
              apple lemon
           2: pear orange


-       As  well as the usual options for pcre2_match(), a number of additional
+       As well as the usual options for pcre2_match(), a number of  additional
        options can be set in the options argument of pcre2_substitute().


        PCRE2_SUBSTITUTE_GLOBAL causes the function to iterate over the subject
-       string,  replacing every matching substring. If this option is not set,
-       only the first matching substring is replaced. The search  for  matches
-       takes  place in the original subject string (that is, previous replace-
-       ments do not affect it).  Iteration is  implemented  by  advancing  the
-       startoffset  value  for  each search, which is always passed the entire
+       string, replacing every matching substring. If this option is not  set,
+       only  the  first matching substring is replaced. The search for matches
+       takes place in the original subject string (that is, previous  replace-
+       ments  do  not  affect  it).  Iteration is implemented by advancing the
+       startoffset value for each search, which is always  passed  the  entire
        subject string. If an offset limit is set in the match context, search-
        ing stops when that limit is reached.


-       You  can  restrict  the effect of a global substitution to a portion of
+       You can restrict the effect of a global substitution to  a  portion  of
        the subject string by setting either or both of startoffset and an off-
        set limit. Here is a pcre2test example:


@@ -3146,87 +3147,87 @@
          ABC ABC ABC ABC\=offset=3,offset_limit=12
           2: ABC A!C A!C ABC


-       When  continuing  with  global substitutions after matching a substring
+       When continuing with global substitutions after  matching  a  substring
        with zero length, an attempt to find a non-empty match at the same off-
        set is performed.  If this is not successful, the offset is advanced by
        one character except when CRLF is a valid newline sequence and the next
-       two  characters are CR, LF. In this case, the offset is advanced by two
+       two characters are CR, LF. In this case, the offset is advanced by  two
        characters.


-       PCRE2_SUBSTITUTE_OVERFLOW_LENGTH changes what happens when  the  output
+       PCRE2_SUBSTITUTE_OVERFLOW_LENGTH  changes  what happens when the output
        buffer is too small. The default action is to return PCRE2_ERROR_NOMEM-
-       ORY immediately. If this option  is  set,  however,  pcre2_substitute()
+       ORY  immediately.  If  this  option is set, however, pcre2_substitute()
        continues to go through the motions of matching and substituting (with-
-       out, of course, writing anything) in order to compute the size of  buf-
-       fer  that  is  needed.  This  value is passed back via the outlengthptr
-       variable,   with   the   result   of   the   function    still    being
+       out,  of course, writing anything) in order to compute the size of buf-
+       fer that is needed. This value is  passed  back  via  the  outlengthptr
+       variable,    with    the   result   of   the   function   still   being
        PCRE2_ERROR_NOMEMORY.


-       Passing  a  buffer  size  of zero is a permitted way of finding out how
-       much memory is needed for given substitution. However, this  does  mean
+       Passing a buffer size of zero is a permitted way  of  finding  out  how
+       much  memory  is needed for given substitution. However, this does mean
        that the entire operation is carried out twice. Depending on the appli-
-       cation, it may be more efficient to allocate a large  buffer  and  free
-       the   excess   afterwards,   instead  of  using  PCRE2_SUBSTITUTE_OVER-
+       cation,  it  may  be more efficient to allocate a large buffer and free
+       the  excess  afterwards,  instead   of   using   PCRE2_SUBSTITUTE_OVER-
        FLOW_LENGTH.


-       PCRE2_SUBSTITUTE_UNKNOWN_UNSET causes references  to  capturing  groups
-       that  do  not appear in the pattern to be treated as unset groups. This
-       option should be used with care, because it means  that  a  typo  in  a
-       group  name  or  number  no  longer  causes the PCRE2_ERROR_NOSUBSTRING
+       PCRE2_SUBSTITUTE_UNKNOWN_UNSET  causes  references  to capturing groups
+       that do not appear in the pattern to be treated as unset  groups.  This
+       option  should  be  used  with  care, because it means that a typo in a
+       group name or  number  no  longer  causes  the  PCRE2_ERROR_NOSUBSTRING
        error.


-       PCRE2_SUBSTITUTE_UNSET_EMPTY causes unset capturing  groups  (including
+       PCRE2_SUBSTITUTE_UNSET_EMPTY  causes  unset capturing groups (including
        unknown  groups  when  PCRE2_SUBSTITUTE_UNKNOWN_UNSET  is  set)  to  be
-       treated as empty strings when inserted  as  described  above.  If  this
-       option  is  not  set,  an  attempt  to insert an unset group causes the
-       PCRE2_ERROR_UNSET error. This option does not  influence  the  extended
+       treated  as  empty  strings  when  inserted as described above. If this
+       option is not set, an attempt to  insert  an  unset  group  causes  the
+       PCRE2_ERROR_UNSET  error.  This  option does not influence the extended
        substitution syntax described below.


-       PCRE2_SUBSTITUTE_EXTENDED  causes extra processing to be applied to the
-       replacement string. Without this option, only the dollar  character  is
-       special,  and  only  the  group insertion forms listed above are valid.
+       PCRE2_SUBSTITUTE_EXTENDED causes extra processing to be applied to  the
+       replacement  string.  Without this option, only the dollar character is
+       special, and only the group insertion forms  listed  above  are  valid.
        When PCRE2_SUBSTITUTE_EXTENDED is set, two things change:


-       Firstly, backslash in a replacement string is interpreted as an  escape
+       Firstly,  backslash in a replacement string is interpreted as an escape
        character. The usual forms such as \n or \x{ddd} can be used to specify
-       particular character codes, and backslash followed by any  non-alphanu-
-       meric  character  quotes  that character. Extended quoting can be coded
+       particular  character codes, and backslash followed by any non-alphanu-
+       meric character quotes that character. Extended quoting  can  be  coded
        using \Q...\E, exactly as in pattern strings.


-       There are also four escape sequences for forcing the case  of  inserted
-       letters.   The  insertion  mechanism has three states: no case forcing,
+       There  are  also four escape sequences for forcing the case of inserted
+       letters.  The insertion mechanism has three states:  no  case  forcing,
        force upper case, and force lower case. The escape sequences change the
        current state: \U and \L change to upper or lower case forcing, respec-
-       tively, and \E (when not terminating a \Q quoted sequence)  reverts  to
-       no  case  forcing. The sequences \u and \l force the next character (if
-       it is a letter) to upper or lower  case,  respectively,  and  then  the
+       tively,  and  \E (when not terminating a \Q quoted sequence) reverts to
+       no case forcing. The sequences \u and \l force the next  character  (if
+       it  is  a  letter)  to  upper or lower case, respectively, and then the
        state automatically reverts to no case forcing. Case forcing applies to
        all inserted  characters, including those from captured groups and let-
        ters within \Q...\E quoted sequences.


        Note that case forcing sequences such as \U...\E do not nest. For exam-
-       ple, the result of processing "\Uaa\LBB\Ecc\E" is "AAbbcc";  the  final
+       ple,  the  result of processing "\Uaa\LBB\Ecc\E" is "AAbbcc"; the final
        \E has no effect.


-       The  second  effect of setting PCRE2_SUBSTITUTE_EXTENDED is to add more
-       flexibility to group substitution. The syntax is similar to  that  used
+       The second effect of setting PCRE2_SUBSTITUTE_EXTENDED is to  add  more
+       flexibility  to  group substitution. The syntax is similar to that used
        by Bash:


          ${<n>:-<string>}
          ${<n>:+<string1>:<string2>}


-       As  before,  <n> may be a group number or a name. The first form speci-
-       fies a default value. If group <n> is set, its value  is  inserted;  if
-       not,  <string>  is  expanded  and  the result inserted. The second form
-       specifies strings that are expanded and inserted when group <n> is  set
-       or  unset,  respectively. The first form is just a convenient shorthand
+       As before, <n> may be a group number or a name. The first  form  speci-
+       fies  a  default  value. If group <n> is set, its value is inserted; if
+       not, <string> is expanded and the  result  inserted.  The  second  form
+       specifies  strings that are expanded and inserted when group <n> is set
+       or unset, respectively. The first form is just a  convenient  shorthand
        for


          ${<n>:+${<n>}:<string>}


-       Backslash can be used to escape colons and closing  curly  brackets  in
-       the  replacement  strings.  A change of the case forcing state within a
-       replacement string remains  in  force  afterwards,  as  shown  in  this
+       Backslash  can  be  used to escape colons and closing curly brackets in
+       the replacement strings. A change of the case forcing  state  within  a
+       replacement  string  remains  in  force  afterwards,  as  shown in this
        pcre2test example:


          /(some)?(body)/substitute_extended,replace=${1:+\U:\L}HeLLo
@@ -3235,16 +3236,16 @@
              somebody
           1: HELLO


-       The  PCRE2_SUBSTITUTE_UNSET_EMPTY option does not affect these extended
-       substitutions.  However,  PCRE2_SUBSTITUTE_UNKNOWN_UNSET   does   cause
+       The PCRE2_SUBSTITUTE_UNSET_EMPTY option does not affect these  extended
+       substitutions.   However,   PCRE2_SUBSTITUTE_UNKNOWN_UNSET  does  cause
        unknown groups in the extended syntax forms to be treated as unset.


-       If  successful,  pcre2_substitute()  returns the number of replacements
+       If successful, pcre2_substitute() returns the  number  of  replacements
        that were made. This may be zero if no matches were found, and is never
        greater than 1 unless PCRE2_SUBSTITUTE_GLOBAL is set.


        In the event of an error, a negative error code is returned. Except for
-       PCRE2_ERROR_NOMATCH   (which   is   never   returned),   errors    from
+       PCRE2_ERROR_NOMATCH    (which   is   never   returned),   errors   from
        pcre2_match() are passed straight back.


        PCRE2_ERROR_NOSUBSTRING is returned for a non-existent substring inser-
@@ -3251,26 +3252,26 @@
        tion, unless PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set.


        PCRE2_ERROR_UNSET is returned for an unset substring insertion (includ-
-       ing  an  unknown  substring when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set)
+       ing an unknown substring when  PCRE2_SUBSTITUTE_UNKNOWN_UNSET  is  set)
        when  the  simple  (non-extended)  syntax  is  used  and  PCRE2_SUBSTI-
        TUTE_UNSET_EMPTY is not set.


-       PCRE2_ERROR_NOMEMORY  is  returned  if  the  output  buffer  is not big
+       PCRE2_ERROR_NOMEMORY is returned  if  the  output  buffer  is  not  big
        enough. If the PCRE2_SUBSTITUTE_OVERFLOW_LENGTH option is set, the size
-       of  buffer  that is needed is returned via outlengthptr. Note that this
+       of buffer that is needed is returned via outlengthptr. Note  that  this
        does not happen by default.


-       PCRE2_ERROR_BADREPLACEMENT is used for miscellaneous syntax  errors  in
+       PCRE2_ERROR_BADREPLACEMENT  is  used for miscellaneous syntax errors in
        the   replacement   string,   with   more   particular   errors   being
-       PCRE2_ERROR_BADREPESCAPE (invalid  escape  sequence),  PCRE2_ERROR_REP-
-       MISSINGBRACE  (closing curly bracket not found), PCRE2_ERROR_BADSUBSTI-
+       PCRE2_ERROR_BADREPESCAPE  (invalid  escape  sequence), PCRE2_ERROR_REP-
+       MISSINGBRACE (closing curly bracket not found),  PCRE2_ERROR_BADSUBSTI-
        TUTION   (syntax   error   in   extended   group   substitution),   and
-       PCRE2_ERROR_BADSUBSPATTERN  (the  pattern match ended before it started
-       or the match started earlier than the current position in the  subject,
+       PCRE2_ERROR_BADSUBSPATTERN (the pattern match ended before  it  started
+       or  the match started earlier than the current position in the subject,
        which can happen if \K is used in an assertion).


        As for all PCRE2 errors, a text message that describes the error can be
-       obtained  by  calling  the  pcre2_get_error_message()   function   (see
+       obtained   by   calling  the  pcre2_get_error_message()  function  (see
        "Obtaining a textual error message" above).



@@ -3279,56 +3280,56 @@
        int pcre2_substring_nametable_scan(const pcre2_code *code,
          PCRE2_SPTR name, PCRE2_SPTR *first, PCRE2_SPTR *last);


-       When  a  pattern  is compiled with the PCRE2_DUPNAMES option, names for
-       subpatterns are not required to be unique. Duplicate names  are  always
-       allowed  for subpatterns with the same number, created by using the (?|
-       feature. Indeed, if such subpatterns are named, they  are  required  to
+       When a pattern is compiled with the PCRE2_DUPNAMES  option,  names  for
+       subpatterns  are  not required to be unique. Duplicate names are always
+       allowed for subpatterns with the same number, created by using the  (?|
+       feature.  Indeed,  if  such subpatterns are named, they are required to
        use the same names.


        Normally, patterns with duplicate names are such that in any one match,
-       only one of the named subpatterns participates. An example is shown  in
+       only  one of the named subpatterns participates. An example is shown in
        the pcre2pattern documentation.


-       When   duplicates   are   present,   pcre2_substring_copy_byname()  and
-       pcre2_substring_get_byname() return the first  substring  corresponding
-       to   the   given   name   that   is  set.  Only  if  none  are  set  is
-       PCRE2_ERROR_UNSET is returned.  The  pcre2_substring_number_from_name()
+       When  duplicates   are   present,   pcre2_substring_copy_byname()   and
+       pcre2_substring_get_byname()  return  the first substring corresponding
+       to  the  given  name  that  is  set.  Only   if   none   are   set   is
+       PCRE2_ERROR_UNSET  is  returned. The pcre2_substring_number_from_name()
        function returns the error PCRE2_ERROR_NOUNIQUESUBSTRING when there are
        duplicate names.


-       If you want to get full details of all captured substrings for a  given
-       name,  you  must use the pcre2_substring_nametable_scan() function. The
-       first argument is the compiled pattern, and the second is the name.  If
-       the  third  and fourth arguments are NULL, the function returns a group
+       If  you want to get full details of all captured substrings for a given
+       name, you must use the pcre2_substring_nametable_scan()  function.  The
+       first  argument is the compiled pattern, and the second is the name. If
+       the third and fourth arguments are NULL, the function returns  a  group
        number for a unique name, or PCRE2_ERROR_NOUNIQUESUBSTRING otherwise.


        When the third and fourth arguments are not NULL, they must be pointers
-       to  variables  that are updated by the function. After it has run, they
+       to variables that are updated by the function. After it has  run,  they
        point to the first and last entries in the name-to-number table for the
-       given  name,  and the function returns the length of each entry in code
-       units. In both cases, PCRE2_ERROR_NOSUBSTRING is returned if there  are
+       given name, and the function returns the length of each entry  in  code
+       units.  In both cases, PCRE2_ERROR_NOSUBSTRING is returned if there are
        no entries for the given name.


        The format of the name table is described above in the section entitled
-       Information about a pattern. Given all the  relevant  entries  for  the
-       name,  you  can  extract  each of their numbers, and hence the captured
+       Information  about  a  pattern.  Given all the relevant entries for the
+       name, you can extract each of their numbers,  and  hence  the  captured
        data.



FINDING ALL POSSIBLE MATCHES AT ONE POSITION

-       The traditional matching function uses a  similar  algorithm  to  Perl,
-       which  stops when it finds the first match at a given point in the sub-
+       The  traditional  matching  function  uses a similar algorithm to Perl,
+       which stops when it finds the first match at a given point in the  sub-
        ject. If you want to find all possible matches, or the longest possible
-       match  at  a  given  position,  consider using the alternative matching
-       function (see below) instead. If you cannot use the  alternative  func-
+       match at a given position,  consider  using  the  alternative  matching
+       function  (see  below) instead. If you cannot use the alternative func-
        tion, you can kludge it up by making use of the callout facility, which
        is described in the pcre2callout documentation.


        What you have to do is to insert a callout right at the end of the pat-
-       tern.   When your callout function is called, extract and save the cur-
-       rent matched substring. Then return 1, which  forces  pcre2_match()  to
-       backtrack  and  try other alternatives. Ultimately, when it runs out of
+       tern.  When your callout function is called, extract and save the  cur-
+       rent  matched  substring.  Then return 1, which forces pcre2_match() to
+       backtrack and try other alternatives. Ultimately, when it runs  out  of
        matches, pcre2_match() will yield PCRE2_ERROR_NOMATCH.



@@ -3340,26 +3341,26 @@
          pcre2_match_context *mcontext,
          int *workspace, PCRE2_SIZE wscount);


-       The function pcre2_dfa_match() is called  to  match  a  subject  string
-       against  a  compiled pattern, using a matching algorithm that scans the
+       The  function  pcre2_dfa_match()  is  called  to match a subject string
+       against a compiled pattern, using a matching algorithm that  scans  the
        subject string just once (not counting lookaround assertions), and does
-       not  backtrack.  This has different characteristics to the normal algo-
-       rithm, and is not compatible with Perl. Some of the features  of  PCRE2
-       patterns  are  not  supported.  Nevertheless, there are times when this
-       kind of matching can be useful. For a discussion of  the  two  matching
+       not backtrack.  This has different characteristics to the normal  algo-
+       rithm,  and  is not compatible with Perl. Some of the features of PCRE2
+       patterns are not supported.  Nevertheless, there are  times  when  this
+       kind  of  matching  can be useful. For a discussion of the two matching
        algorithms, and a list of features that pcre2_dfa_match() does not sup-
        port, see the pcre2matching documentation.


-       The arguments for the pcre2_dfa_match() function are the  same  as  for
+       The  arguments  for  the pcre2_dfa_match() function are the same as for
        pcre2_match(), plus two extras. The ovector within the match data block
        is used in a different way, and this is described below. The other com-
-       mon  arguments  are used in the same way as for pcre2_match(), so their
+       mon arguments are used in the same way as for pcre2_match(),  so  their
        description is not repeated here.


-       The two additional arguments provide workspace for  the  function.  The
-       workspace  vector  should  contain at least 20 elements. It is used for
+       The  two  additional  arguments provide workspace for the function. The
+       workspace vector should contain at least 20 elements. It  is  used  for
        keeping  track  of  multiple  paths  through  the  pattern  tree.  More
-       workspace  is needed for patterns and subjects where there are a lot of
+       workspace is needed for patterns and subjects where there are a lot  of
        potential matches.


        Here is an example of a simple call to pcre2_dfa_match():
@@ -3379,45 +3380,45 @@


    Option bits for pcre_dfa_match()


-       The unused bits of the options argument for pcre2_dfa_match()  must  be
-       zero.  The  only  bits that may be set are PCRE2_ANCHORED, PCRE2_ENDAN-
-       CHORED,       PCRE2_NOTBOL,        PCRE2_NOTEOL,        PCRE2_NOTEMPTY,
+       The  unused  bits of the options argument for pcre2_dfa_match() must be
+       zero. The only bits that may be set  are  PCRE2_ANCHORED,  PCRE2_ENDAN-
+       CHORED,        PCRE2_NOTBOL,        PCRE2_NOTEOL,       PCRE2_NOTEMPTY,
        PCRE2_NOTEMPTY_ATSTART,     PCRE2_NO_UTF_CHECK,     PCRE2_PARTIAL_HARD,
-       PCRE2_PARTIAL_SOFT, PCRE2_DFA_SHORTEST, and PCRE2_DFA_RESTART. All  but
-       the  last  four  of these are exactly the same as for pcre2_match(), so
+       PCRE2_PARTIAL_SOFT,  PCRE2_DFA_SHORTEST, and PCRE2_DFA_RESTART. All but
+       the last four of these are exactly the same as  for  pcre2_match(),  so
        their description is not repeated here.


          PCRE2_PARTIAL_HARD
          PCRE2_PARTIAL_SOFT


-       These have the same general effect as they do  for  pcre2_match(),  but
-       the  details are slightly different. When PCRE2_PARTIAL_HARD is set for
-       pcre2_dfa_match(), it returns PCRE2_ERROR_PARTIAL if  the  end  of  the
+       These  have  the  same general effect as they do for pcre2_match(), but
+       the details are slightly different. When PCRE2_PARTIAL_HARD is set  for
+       pcre2_dfa_match(),  it  returns  PCRE2_ERROR_PARTIAL  if the end of the
        subject is reached and there is still at least one matching possibility
        that requires additional characters. This happens even if some complete
-       matches  have  already  been found. When PCRE2_PARTIAL_SOFT is set, the
-       return code PCRE2_ERROR_NOMATCH is converted  into  PCRE2_ERROR_PARTIAL
-       if  the  end  of  the  subject  is reached, there have been no complete
+       matches have already been found. When PCRE2_PARTIAL_SOFT  is  set,  the
+       return  code  PCRE2_ERROR_NOMATCH is converted into PCRE2_ERROR_PARTIAL
+       if the end of the subject is  reached,  there  have  been  no  complete
        matches, but there is still at least one matching possibility. The por-
-       tion  of  the  string that was inspected when the longest partial match
+       tion of the string that was inspected when the  longest  partial  match
        was found is set as the first matching string in both cases. There is a
-       more  detailed  discussion  of partial and multi-segment matching, with
+       more detailed discussion of partial and  multi-segment  matching,  with
        examples, in the pcre2partial documentation.


          PCRE2_DFA_SHORTEST


-       Setting the PCRE2_DFA_SHORTEST option causes the matching algorithm  to
+       Setting  the PCRE2_DFA_SHORTEST option causes the matching algorithm to
        stop as soon as it has found one match. Because of the way the alterna-
-       tive algorithm works, this is necessarily the shortest  possible  match
+       tive  algorithm  works, this is necessarily the shortest possible match
        at the first possible matching point in the subject string.


          PCRE2_DFA_RESTART


-       When  pcre2_dfa_match() returns a partial match, it is possible to call
+       When pcre2_dfa_match() returns a partial match, it is possible to  call
        it again, with additional subject characters, and have it continue with
        the same match. The PCRE2_DFA_RESTART option requests this action; when
-       it is set, the workspace and wscount options must  reference  the  same
-       vector  as  before  because data about the match so far is left in them
+       it  is  set,  the workspace and wscount options must reference the same
+       vector as before because data about the match so far is  left  in  them
        after a partial match. There is more discussion of this facility in the
        pcre2partial documentation.


@@ -3425,8 +3426,8 @@

        When pcre2_dfa_match() succeeds, it may have matched more than one sub-
        string in the subject. Note, however, that all the matches from one run
-       of  the  function  start  at the same point in the subject. The shorter
-       matches are all initial substrings of the longer matches. For  example,
+       of the function start at the same point in  the  subject.  The  shorter
+       matches  are all initial substrings of the longer matches. For example,
        if the pattern


          <.*>
@@ -3441,73 +3442,73 @@
          <something> <something else>
          <something>


-       On  success,  the  yield of the function is a number greater than zero,
-       which is the number of matched substrings.  The  offsets  of  the  sub-
-       strings  are returned in the ovector, and can be extracted by number in
-       the same way as for pcre2_match(), but the numbers bear no relation  to
-       any  capturing groups that may exist in the pattern, because DFA match-
+       On success, the yield of the function is a number  greater  than  zero,
+       which  is  the  number  of  matched substrings. The offsets of the sub-
+       strings are returned in the ovector, and can be extracted by number  in
+       the  same way as for pcre2_match(), but the numbers bear no relation to
+       any capturing groups that may exist in the pattern, because DFA  match-
        ing does not support group capture.


-       Calls to the convenience functions  that  extract  substrings  by  name
-       return  the  error PCRE2_ERROR_DFA_UFUNC (unsupported function) if used
+       Calls  to  the  convenience  functions  that extract substrings by name
+       return the error PCRE2_ERROR_DFA_UFUNC (unsupported function)  if  used
        after a DFA match. The convenience functions that extract substrings by
        number never return PCRE2_ERROR_NOSUBSTRING.


-       The  matched  strings  are  stored  in  the ovector in reverse order of
-       length; that is, the longest matching string is first.  If  there  were
-       too  many matches to fit into the ovector, the yield of the function is
+       The matched strings are stored in  the  ovector  in  reverse  order  of
+       length;  that  is,  the longest matching string is first. If there were
+       too many matches to fit into the ovector, the yield of the function  is
        zero, and the vector is filled with the longest matches.


-       NOTE: PCRE2's "auto-possessification" optimization usually  applies  to
-       character  repeats at the end of a pattern (as well as internally). For
-       example, the pattern "a\d+" is compiled as if it were "a\d++". For  DFA
-       matching,  this  means  that  only  one possible match is found. If you
-       really do want multiple matches in such cases, either use  an  ungreedy
-       repeat  such  as  "a\d+?"  or set the PCRE2_NO_AUTO_POSSESS option when
+       NOTE:  PCRE2's  "auto-possessification" optimization usually applies to
+       character repeats at the end of a pattern (as well as internally).  For
+       example,  the pattern "a\d+" is compiled as if it were "a\d++". For DFA
+       matching, this means that only one possible  match  is  found.  If  you
+       really  do  want multiple matches in such cases, either use an ungreedy
+       repeat such as "a\d+?" or set  the  PCRE2_NO_AUTO_POSSESS  option  when
        compiling.


    Error returns from pcre2_dfa_match()


        The pcre2_dfa_match() function returns a negative number when it fails.
-       Many  of  the  errors  are  the same as for pcre2_match(), as described
+       Many of the errors are the same  as  for  pcre2_match(),  as  described
        above.  There are in addition the following errors that are specific to
        pcre2_dfa_match():


          PCRE2_ERROR_DFA_UITEM


-       This  return  is  given  if pcre2_dfa_match() encounters an item in the
-       pattern that it does not support, for instance, the use of \C in a  UTF
+       This return is given if pcre2_dfa_match() encounters  an  item  in  the
+       pattern  that it does not support, for instance, the use of \C in a UTF
        mode or a backreference.


          PCRE2_ERROR_DFA_UCOND


-       This  return  is given if pcre2_dfa_match() encounters a condition item
+       This return is given if pcre2_dfa_match() encounters a  condition  item
        that uses a backreference for the condition, or a test for recursion in
        a specific group. These are not supported.


          PCRE2_ERROR_DFA_WSSIZE


-       This  return  is  given  if  pcre2_dfa_match() runs out of space in the
+       This return is given if pcre2_dfa_match() runs  out  of  space  in  the
        workspace vector.


          PCRE2_ERROR_DFA_RECURSE


-       When a recursive subpattern is processed, the matching  function  calls
+       When  a  recursive subpattern is processed, the matching function calls
        itself recursively, using private memory for the ovector and workspace.
-       This error is given if the internal ovector is not large  enough.  This
+       This  error  is given if the internal ovector is not large enough. This
        should be extremely rare, as a vector of size 1000 is used.


          PCRE2_ERROR_DFA_BADRESTART


-       When  pcre2_dfa_match()  is  called  with the PCRE2_DFA_RESTART option,
-       some plausibility checks are made on the  contents  of  the  workspace,
-       which  should  contain data about the previous partial match. If any of
+       When pcre2_dfa_match() is called  with  the  PCRE2_DFA_RESTART  option,
+       some  plausibility  checks  are  made on the contents of the workspace,
+       which should contain data about the previous partial match. If  any  of
        these checks fail, this error is given.



SEE ALSO

-       pcre2build(3),   pcre2callout(3),    pcre2demo(3),    pcre2matching(3),
+       pcre2build(3),    pcre2callout(3),    pcre2demo(3),   pcre2matching(3),
        pcre2partial(3), pcre2posix(3), pcre2sample(3), pcre2unicode(3).



@@ -3520,7 +3521,7 @@

REVISION

-       Last updated: 02 July 2018
+       Last updated: 27 July 2018
        Copyright (c) 1997-2018 University of Cambridge.
 ------------------------------------------------------------------------------


@@ -4536,157 +4537,164 @@
        when  a  negative  assertion  is a condition that has a matching branch
        (that is, the condition is false).


-       4. The following Perl escape sequences are not supported: \l,  \u,  \L,
-       \U,  and  \N when followed by a character name or Unicode value. (\N on
-       its own, matching a non-newline character, is supported.) In fact these
-       are  implemented  by Perl's general string-handling and are not part of
-       its pattern matching engine. If any of these are encountered by  PCRE2,
-       an error is generated by default. However, if the PCRE2_ALT_BSUX option
-       is set, \U and \u are interpreted as ECMAScript interprets them.
+       4. The following Perl escape sequences are not supported: \F,  \l,  \L,
+       \u, \U, and \N when followed by a character name. \N on its own, match-
+       ing a non-newline character, and \N{U+dd..}, matching  a  Unicode  code
+       point,  are  supported.  The  escapes that modify the case of following
+       letters are implemented by Perl's general string-handling and  are  not
+       part of its pattern matching engine. If any of these are encountered by
+       PCRE2, an error is generated by default. However, if the PCRE2_ALT_BSUX
+       option is set, \U and \u are interpreted as ECMAScript interprets them.


        5. The Perl escape sequences \p, \P, and \X are supported only if PCRE2
        is built with Unicode support (the default). The properties that can be
-       tested with \p and \P are limited to the  general  category  properties
-       such  as  Lu and Nd, script names such as Greek or Han, and the derived
+       tested  with  \p  and \P are limited to the general category properties
+       such as Lu and Nd, script names such as Greek or Han, and  the  derived
        properties Any and L&.  PCRE2 does support the Cs (surrogate) property,
-       which  Perl  does  not; the Perl documentation says "Because Perl hides
+       which Perl does not; the Perl documentation says  "Because  Perl  hides
        the need for the user to understand the internal representation of Uni-
-       code  characters, there is no need to implement the somewhat messy con-
+       code characters, there is no need to implement the somewhat messy  con-
        cept of surrogates."


-       6. PCRE2 does support the \Q...\E escape for quoting substrings.  Char-
-       acters  in  between are treated as literals. This is slightly different
-       from Perl in that $ and @ are  also  handled  as  literals  inside  the
+       6. PCRE2 supports the \Q...\E escape for quoting substrings. Characters
+       in between are treated as literals. However, this is slightly different
+       from  Perl  in  that  $  and  @ are also handled as literals inside the
        quotes. In Perl, they cause variable interpolation (but of course PCRE2
-       does not have variables).  Note the following examples:
+       does  not  have  variables).  Also, Perl does "double-quotish backslash
+       interpolation" on any backslashes between \Q and \E which, its documen-
+       tation  says, "may lead to confusing results". PCRE2 treats a backslash
+       between \Q and \E just like any other  character.  Note  the  following
+       examples:


-           Pattern            PCRE2 matches      Perl matches
+           Pattern            PCRE2 matches     Perl matches


            \Qabc$xyz\E        abc$xyz           abc followed by the
                                                   contents of $xyz
            \Qabc\$xyz\E       abc\$xyz          abc\$xyz
            \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
+           \QA\B\E            A\B               A\B
+           \Q\\E              \                 \\E


-       The \Q...\E sequence is recognized both inside  and  outside  character
+       The  \Q...\E  sequence  is recognized both inside and outside character
        classes.


-       7.   Fairly  obviously,  PCRE2  does  not  support  the  (?{code})  and
+       7.  Fairly  obviously,  PCRE2  does  not  support  the  (?{code})   and
        (??{code}) constructions. However, PCRE2 does have a "callout" feature,
        which allows an external function to be called during pattern matching.
        See the pcre2callout documentation for details.


-       8. Subroutine calls (whether recursive or not) were treated  as  atomic
-       groups  up to PCRE2 release 10.23, but from release 10.30 this changed,
+       8.  Subroutine  calls (whether recursive or not) were treated as atomic
+       groups up to PCRE2 release 10.23, but from release 10.30 this  changed,
        and backtracking into subroutine calls is now supported, as in Perl.


-       9. If any of the backtracking control verbs are used  in  a  subpattern
-       that  is  called  as  a  subroutine (whether or not recursively), their
-       effect is confined to that subpattern; it does not extend to  the  sur-
-       rounding  pattern.  This is not always the case in Perl. In particular,
-       if (*THEN) is present in a group that is called as  a  subroutine,  its
+       9.  If  any  of the backtracking control verbs are used in a subpattern
+       that is called as a subroutine  (whether  or  not  recursively),  their
+       effect  is  confined to that subpattern; it does not extend to the sur-
+       rounding pattern. This is not always the case in Perl.  In  particular,
+       if  (*THEN)  is  present in a group that is called as a subroutine, its
        action is limited to that group, even if the group does not contain any
-       | characters. Note that such subpatterns are processed as  anchored  at
+       |  characters.  Note that such subpatterns are processed as anchored at
        the point where they are tested.


-       10.  If a pattern contains more than one backtracking control verb, the
-       first one that is backtracked onto acts. For example,  in  the  pattern
-       A(*COMMIT)B(*PRUNE)C  a  failure in B triggers (*COMMIT), but a failure
+       10. If a pattern contains more than one backtracking control verb,  the
+       first  one  that  is backtracked onto acts. For example, in the pattern
+       A(*COMMIT)B(*PRUNE)C a failure in B triggers (*COMMIT), but  a  failure
        in C triggers (*PRUNE). Perl's behaviour is more complex; in many cases
        it is the same as PCRE2, but there are cases where it differs.


-       11.  Most  backtracking  verbs in assertions have their normal actions.
+       11. Most backtracking verbs in assertions have  their  normal  actions.
        They are not confined to the assertion.


-       12. There are some differences that are concerned with the settings  of
-       captured  strings  when  part  of  a  pattern is repeated. For example,
-       matching "aba" against the  pattern  /^(a(b)?)+$/  in  Perl  leaves  $2
+       12.  There are some differences that are concerned with the settings of
+       captured strings when part of  a  pattern  is  repeated.  For  example,
+       matching  "aba"  against  the  pattern  /^(a(b)?)+$/  in Perl leaves $2
        unset, but in PCRE2 it is set to "b".


        13. PCRE2's handling of duplicate subpattern numbers and duplicate sub-
        pattern names is not as general as Perl's. This is a consequence of the
-       fact  the  PCRE2  works internally just with numbers, using an external
-       table to translate between numbers and names. In particular, a  pattern
-       such  as  (?|(?<a>A)|(?<b>B),  where the two capturing parentheses have
-       the same number but different names, is not supported,  and  causes  an
-       error  at compile time. If it were allowed, it would not be possible to
-       distinguish which parentheses matched, because both names map  to  cap-
+       fact the PCRE2 works internally just with numbers,  using  an  external
+       table  to translate between numbers and names. In particular, a pattern
+       such as (?|(?<a>A)|(?<b>B), where the two  capturing  parentheses  have
+       the  same  number  but different names, is not supported, and causes an
+       error at compile time. If it were allowed, it would not be possible  to
+       distinguish  which  parentheses matched, because both names map to cap-
        turing subpattern number 1. To avoid this confusing situation, an error
        is given at compile time.


        14. Perl used to recognize comments in some places that PCRE2 does not,
-       for  example,  between the ( and ? at the start of a subpattern. If the
+       for example, between the ( and ? at the start of a subpattern.  If  the
        /x modifier is set, Perl allowed white space between ( and ? though the
-       latest  Perls give an error (for a while it was just deprecated). There
+       latest Perls give an error (for a while it was just deprecated).  There
        may still be some cases where Perl behaves differently.


-       15. Perl, when in warning mode, gives warnings  for  character  classes
-       such  as  [A-\d] or [a-[:digit:]]. It then treats the hyphens as liter-
+       15.  Perl,  when  in warning mode, gives warnings for character classes
+       such as [A-\d] or [a-[:digit:]]. It then treats the hyphens  as  liter-
        als. PCRE2 has no warning features, so it gives an error in these cases
        because they are almost certainly user mistakes.


-       16.  In  PCRE2, the upper/lower case character properties Lu and Ll are
-       not affected when case-independent matching is specified. For  example,
+       16. In PCRE2, the upper/lower case character properties Lu and  Ll  are
+       not  affected when case-independent matching is specified. For example,
        \p{Lu} always matches an upper case letter. I think Perl has changed in
-       this respect; in the release at the time of writing (5.24), \p{Lu}  and
+       this  respect; in the release at the time of writing (5.24), \p{Lu} and
        \p{Ll} match all letters, regardless of case, when case independence is
        specified.


-       17. PCRE2 provides some  extensions  to  the  Perl  regular  expression
-       facilities.   Perl  5.10  includes new features that are not in earlier
-       versions of Perl, some of which (such as  named  parentheses)  were  in
+       17.  PCRE2  provides  some  extensions  to  the Perl regular expression
+       facilities.  Perl 5.10 includes new features that are  not  in  earlier
+       versions  of  Perl,  some  of which (such as named parentheses) were in
        PCRE2 for some time before. This list is with respect to Perl 5.26:


-       (a)  Although  lookbehind  assertions  in PCRE2 must match fixed length
-       strings, each alternative branch of a lookbehind assertion can match  a
-       different  length  of  string.  Perl requires them all to have the same
+       (a) Although lookbehind assertions in PCRE2  must  match  fixed  length
+       strings,  each alternative branch of a lookbehind assertion can match a
+       different length of string. Perl requires them all  to  have  the  same
        length.


        (b) From PCRE2 10.23, backreferences to groups of fixed length are sup-
-       ported  in lookbehinds, provided that there is no possibility of refer-
-       encing a non-unique number or name. Perl does  not  support  backrefer-
+       ported in lookbehinds, provided that there is no possibility of  refer-
+       encing  a  non-unique  number or name. Perl does not support backrefer-
        ences in lookbehinds.


-       (c)  If PCRE2_DOLLAR_ENDONLY is set and PCRE2_MULTILINE is not set, the
+       (c) If PCRE2_DOLLAR_ENDONLY is set and PCRE2_MULTILINE is not set,  the
        $ meta-character matches only at the very end of the string.


-       (d) A backslash followed  by  a  letter  with  no  special  meaning  is
+       (d)  A  backslash  followed  by  a  letter  with  no special meaning is
        faulted. (Perl can be made to issue a warning.)


-       (e)  If PCRE2_UNGREEDY is set, the greediness of the repetition quanti-
+       (e) If PCRE2_UNGREEDY is set, the greediness of the repetition  quanti-
        fiers is inverted, that is, by default they are not greedy, but if fol-
        lowed by a question mark they are.


-       (f)  PCRE2_ANCHORED  can be used at matching time to force a pattern to
+       (f) PCRE2_ANCHORED can be used at matching time to force a  pattern  to
        be tried only at the first matching position in the subject string.


-       (g)    The    PCRE2_NOTBOL,    PCRE2_NOTEOL,     PCRE2_NOTEMPTY     and
+       (g)     The     PCRE2_NOTBOL,    PCRE2_NOTEOL,    PCRE2_NOTEMPTY    and
        PCRE2_NOTEMPTY_ATSTART options have no Perl equivalents.


-       (h)  The  \R escape sequence can be restricted to match only CR, LF, or
+       (h) The \R escape sequence can be restricted to match only CR,  LF,  or
        CRLF by the PCRE2_BSR_ANYCRLF option.


-       (i) The callout facility is PCRE2-specific.  Perl  supports  codeblocks
+       (i)  The  callout  facility is PCRE2-specific. Perl supports codeblocks
        and variable interpolation, but not general hooks on every match.


        (j) The partial matching facility is PCRE2-specific.


-       (k)  The  alternative matching function (pcre2_dfa_match() matches in a
+       (k) The alternative matching function (pcre2_dfa_match() matches  in  a
        different way and is not Perl-compatible.


-       (l) PCRE2 recognizes some special sequences such as (*CR) or  (*NO_JIT)
-       at  the  start  of  a  pattern  that set overall options that cannot be
+       (l)  PCRE2 recognizes some special sequences such as (*CR) or (*NO_JIT)
+       at the start of a pattern that  set  overall  options  that  cannot  be
        changed within the pattern.


-       18. The Perl /a modifier restricts /d numbers to pure  ascii,  and  the
-       /aa  modifier  restricts  /i  case-insensitive  matching to pure ascii,
-       ignoring Unicode rules. This  separation  cannot  be  represented  with
+       18.  The  Perl  /a modifier restricts /d numbers to pure ascii, and the
+       /aa modifier restricts /i  case-insensitive  matching  to  pure  ascii,
+       ignoring  Unicode  rules.  This  separation  cannot be represented with
        PCRE2_UCP.


        19. Perl has different limits than PCRE2. See the pcre2limit documenta-
        tion for details. Perl went with 5.10 from recursion to iteration keep-
        ing the intermediate matches on the heap, which is ~10% slower but does
-       not fall into any stack-overflow limit. PCRE2 made a similar change  at
-       release  10.30,  and also has many build-time and run-time customizable
+       not  fall into any stack-overflow limit. PCRE2 made a similar change at
+       release 10.30, and also has many build-time and  run-time  customizable
        limits.



@@ -4699,8 +4707,8 @@

REVISION

-       Last updated: 18 April 2017
-       Copyright (c) 1997-2017 University of Cambridge.
+       Last updated: 28 July 2018
+       Copyright (c) 1997-2018 University of Cambridge.
 ------------------------------------------------------------------------------



@@ -6121,7 +6129,10 @@
        ters,  you can do so by putting them between \Q and \E. This is differ-
        ent from Perl in that $ and  @  are  handled  as  literals  in  \Q...\E
        sequences  in PCRE2, whereas in Perl, $ and @ cause variable interpola-
-       tion. Note the following examples:
+       tion. Also, Perl does "double-quotish backslash interpolation"  on  any
+       backslashes  between \Q and \E which, its documentation says, "may lead
+       to confusing results". PCRE2 treats a backslash between \Q and \E  just
+       like any other character. Note the following examples:


          Pattern            PCRE2 matches   Perl matches


@@ -6129,22 +6140,24 @@
                                              contents of $xyz
          \Qabc\$xyz\E       abc\$xyz       abc\$xyz
          \Qabc\E\$\Qxyz\E   abc$xyz        abc$xyz
+         \QA\B\E            A\B            A\B
+         \Q\\E              \              \\E


-       The \Q...\E sequence is recognized both inside  and  outside  character
-       classes.   An  isolated \E that is not preceded by \Q is ignored. If \Q
-       is not followed by \E later in the pattern, the literal  interpretation
-       continues  to  the  end  of  the pattern (that is, \E is assumed at the
-       end). If the isolated \Q is inside a character class,  this  causes  an
-       error,  because  the  character  class  is  not terminated by a closing
+       The  \Q...\E  sequence  is recognized both inside and outside character
+       classes.  An isolated \E that is not preceded by \Q is ignored.  If  \Q
+       is  not followed by \E later in the pattern, the literal interpretation
+       continues to the end of the pattern (that is,  \E  is  assumed  at  the
+       end).  If  the  isolated \Q is inside a character class, this causes an
+       error, because the character class  is  not  terminated  by  a  closing
        square bracket.


    Non-printing characters


        A second use of backslash provides a way of encoding non-printing char-
-       acters  in patterns in a visible manner. There is no restriction on the
-       appearance of non-printing characters in a pattern, but when a  pattern
+       acters in patterns in a visible manner. There is no restriction on  the
+       appearance  of non-printing characters in a pattern, but when a pattern
        is being prepared by text editing, it is often easier to use one of the
-       following escape sequences than the binary character it represents.  In
+       following  escape sequences than the binary character it represents. In
        an ASCII or Unicode environment, these escapes are as follows:


          \a          alarm, that is, the BEL character (hex 07)
@@ -6162,51 +6175,51 @@
          \N{U+hhh..} character with Unicode code point hhh..
          \uhhhh      character with hex code hhhh (when PCRE2_ALT_BSUX is set)


-       Note  that  when \N is not followed by an opening brace (curly bracket)
-       it has an entirely different meaning, matching any  character  that  is
-       not  a  newline.  Perl also uses \N{name} to specify characters by Uni-
+       Note that when \N is not followed by an opening brace  (curly  bracket)
+       it  has  an  entirely different meaning, matching any character that is
+       not a newline.  Perl also uses \N{name} to specify characters  by  Uni-
        code name; PCRE2 does not support this.


-       The precise effect of \cx on ASCII characters is as follows: if x is  a
-       lower  case  letter,  it  is converted to upper case. Then bit 6 of the
+       The  precise effect of \cx on ASCII characters is as follows: if x is a
+       lower case letter, it is converted to upper case. Then  bit  6  of  the
        character (hex 40) is inverted. Thus \cA to \cZ become hex 01 to hex 1A
-       (A  is  41, Z is 5A), but \c{ becomes hex 3B ({ is 7B), and \c; becomes
-       hex 7B (; is 3B). If the code unit following \c has a value  less  than
+       (A is 41, Z is 5A), but \c{ becomes hex 3B ({ is 7B), and  \c;  becomes
+       hex  7B  (; is 3B). If the code unit following \c has a value less than
        32 or greater than 126, a compile-time error occurs.


-       When  PCRE2  is  compiled in EBCDIC mode, \N{U+hhh..} is not supported.
+       When PCRE2 is compiled in EBCDIC mode, \N{U+hhh..}  is  not  supported.
        \a, \e, \f, \n, \r, and \t generate the appropriate EBCDIC code values.
        The \c escape is processed as specified for Perl in the perlebcdic doc-
-       ument. The only characters that are allowed after \c are A-Z,  a-z,  or
-       one  of @, [, \, ], ^, _, or ?. Any other character provokes a compile-
-       time error. The sequence \c@ encodes character code  0;  after  \c  the
-       letters  (in either case) encode characters 1-26 (hex 01 to hex 1A); [,
-       \, ], ^, and _ encode characters 27-31 (hex 1B  to  hex  1F),  and  \c?
+       ument.  The  only characters that are allowed after \c are A-Z, a-z, or
+       one of @, [, \, ], ^, _, or ?. Any other character provokes a  compile-
+       time  error.  The  sequence  \c@ encodes character code 0; after \c the
+       letters (in either case) encode characters 1-26 (hex 01 to hex 1A);  [,
+       \,  ],  ^,  and  _  encode characters 27-31 (hex 1B to hex 1F), and \c?
        becomes either 255 (hex FF) or 95 (hex 5F).


-       Thus,  apart  from  \c?, these escapes generate the same character code
-       values as they do in an ASCII environment, though the meanings  of  the
-       values  mostly  differ. For example, \cG always generates code value 7,
+       Thus, apart from \c?, these escapes generate the  same  character  code
+       values  as  they do in an ASCII environment, though the meanings of the
+       values mostly differ. For example, \cG always generates code  value  7,
        which is BEL in ASCII but DEL in EBCDIC.


-       The sequence \c? generates DEL (127, hex 7F) in an  ASCII  environment,
-       but  because  127  is  not a control character in EBCDIC, Perl makes it
-       generate the APC character. Unfortunately, there are  several  variants
-       of  EBCDIC.  In  most  of them the APC character has the value 255 (hex
-       FF), but in the one Perl calls POSIX-BC its value is 95  (hex  5F).  If
+       The  sequence  \c? generates DEL (127, hex 7F) in an ASCII environment,
+       but because 127 is not a control character in  EBCDIC,  Perl  makes  it
+       generate  the  APC character. Unfortunately, there are several variants
+       of EBCDIC. In most of them the APC character has  the  value  255  (hex
+       FF),  but  in  the one Perl calls POSIX-BC its value is 95 (hex 5F). If
        certain other characters have POSIX-BC values, PCRE2 makes \c? generate
        95; otherwise it generates 255.


-       After \0 up to two further octal digits are read. If  there  are  fewer
-       than  two  digits,  just  those  that  are  present  are used. Thus the
+       After  \0  up  to two further octal digits are read. If there are fewer
+       than two digits, just  those  that  are  present  are  used.  Thus  the
        sequence \0\x\015 specifies two binary zeros followed by a CR character
        (code value 13). Make sure you supply two digits after the initial zero
        if the pattern character that follows is itself an octal digit.


-       The escape \o must be followed by a sequence of octal digits,  enclosed
-       in  braces.  An  error occurs if this is not the case. This escape is a
-       recent addition to Perl; it provides way of specifying  character  code
-       points  as  octal  numbers  greater than 0777, and it also allows octal
+       The  escape \o must be followed by a sequence of octal digits, enclosed
+       in braces. An error occurs if this is not the case. This  escape  is  a
+       recent  addition  to Perl; it provides way of specifying character code
+       points as octal numbers greater than 0777, and  it  also  allows  octal
        numbers and backreferences to be unambiguously specified.


        For greater clarity and unambiguity, it is best to avoid following \ by
@@ -6219,16 +6232,16 @@


        Outside a character class, PCRE2 reads the digit and any following dig-
        its as a decimal number. If the number is less than 10, begins with the
-       digit 8 or 9, or if there are at least  that  many  previous  capturing
-       left  parentheses  in the expression, the entire sequence is taken as a
-       backreference. A description of how this works is given later,  follow-
-       ing  the  discussion  of  parenthesized  subpatterns.  Otherwise, up to
+       digit  8  or  9,  or if there are at least that many previous capturing
+       left parentheses in the expression, the entire sequence is taken  as  a
+       backreference.  A description of how this works is given later, follow-
+       ing the discussion of  parenthesized  subpatterns.   Otherwise,  up  to
        three octal digits are read to form a character code.


-       Inside a character class, PCRE2 handles \8 and \9 as the literal  char-
-       acters  "8"  and "9", and otherwise reads up to three octal digits fol-
+       Inside  a character class, PCRE2 handles \8 and \9 as the literal char-
+       acters "8" and "9", and otherwise reads up to three octal  digits  fol-
        lowing the backslash, using them to generate a data character. Any sub-
-       sequent  digits  stand for themselves. For example, outside a character
+       sequent digits stand for themselves. For example, outside  a  character
        class:


          \040   is another way of writing an ASCII space
@@ -6245,31 +6258,31 @@
                    the value 255 (decimal)
          \81    is always a backreference


-       Note that octal values of 100 or greater that are specified using  this
-       syntax  must  not be introduced by a leading zero, because no more than
+       Note  that octal values of 100 or greater that are specified using this
+       syntax must not be introduced by a leading zero, because no  more  than
        three octal digits are ever read.


-       By default, after \x that is not followed by {, from zero to two  hexa-
-       decimal  digits  are  read (letters can be in upper or lower case). Any
+       By  default, after \x that is not followed by {, from zero to two hexa-
+       decimal digits are read (letters can be in upper or  lower  case).  Any
        number of hexadecimal digits may appear between \x{ and }. If a charac-
-       ter  other  than  a  hexadecimal digit appears between \x{ and }, or if
+       ter other than a hexadecimal digit appears between \x{  and  },  or  if
        there is no terminating }, an error occurs.


-       If the PCRE2_ALT_BSUX option is set, the interpretation  of  \x  is  as
+       If  the  PCRE2_ALT_BSUX  option  is set, the interpretation of \x is as
        just described only when it is followed by two hexadecimal digits. Oth-
-       erwise, it matches a literal "x" character. In this mode,  support  for
-       code  points greater than 256 is provided by \u, which must be followed
-       by four hexadecimal digits; otherwise it matches a literal "u"  charac-
+       erwise,  it  matches a literal "x" character. In this mode, support for
+       code points greater than 256 is provided by \u, which must be  followed
+       by  four hexadecimal digits; otherwise it matches a literal "u" charac-
        ter.


        Characters whose value is less than 256 can be defined by either of the
        two syntaxes for \x (or by \u in PCRE2_ALT_BSUX mode). There is no dif-
-       ference  in  the way they are handled. For example, \xdc is exactly the
+       ference in the way they are handled. For example, \xdc is  exactly  the
        same as \x{dc} (or \u00dc in PCRE2_ALT_BSUX mode).


    Constraints on character values


-       Characters that are specified using octal or  hexadecimal  numbers  are
+       Characters  that  are  specified using octal or hexadecimal numbers are
        limited to certain values, as follows:


          8-bit non-UTF mode    no greater than 0xff
@@ -6278,25 +6291,25 @@
          All UTF modes         no greater than 0x10ffff and a valid code point


        Invalid Unicode code points are all those in the range 0xd800 to 0xdfff
-       (the so-called "surrogate" code points). The check  for  these  can  be
-       disabled  by  the  caller  of  pcre2_compile()  by  setting  the option
+       (the  so-called  "surrogate"  code  points). The check for these can be
+       disabled by  the  caller  of  pcre2_compile()  by  setting  the  option
        PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES.


    Escape sequences in character classes


        All the sequences that define a single character value can be used both
-       inside  and  outside character classes. In addition, inside a character
+       inside and outside character classes. In addition, inside  a  character
        class, \b is interpreted as the backspace character (hex 08).


        When not followed by an opening brace, \N is not allowed in a character
-       class.   \B,  \R, and \X are not special inside a character class. Like
-       other unrecognized alphabetic escape sequences, they  cause  an  error.
+       class.  \B, \R, and \X are not special inside a character  class.  Like
+       other  unrecognized  alphabetic  escape sequences, they cause an error.
        Outside a character class, these sequences have different meanings.


    Unsupported escape sequences


-       In  Perl, the sequences \l, \L, \u, and \U are recognized by its string
-       handler and used  to  modify  the  case  of  following  characters.  By
+       In Perl, the sequences \F, \l, \L, \u, and \U  are  recognized  by  its
+       string  handler and used to modify the case of following characters. By
        default, PCRE2 does not support these escape sequences. However, if the
        PCRE2_ALT_BSUX option is set, \U matches a "U" character, and \u can be
        used to define a character by code point, as described above.
@@ -6303,17 +6316,17 @@


    Absolute and relative backreferences


-       The  sequence  \g  followed  by a signed or unsigned number, optionally
-       enclosed in braces, is an absolute or relative backreference.  A  named
-       backreference  can  be  coded as \g{name}. Backreferences are discussed
+       The sequence \g followed by a signed  or  unsigned  number,  optionally
+       enclosed  in  braces, is an absolute or relative backreference. A named
+       backreference can be coded as \g{name}.  Backreferences  are  discussed
        later, following the discussion of parenthesized subpatterns.


    Absolute and relative subroutine calls


-       For compatibility with Oniguruma, the non-Perl syntax \g followed by  a
+       For  compatibility with Oniguruma, the non-Perl syntax \g followed by a
        name or a number enclosed either in angle brackets or single quotes, is
-       an alternative syntax for referencing a subpattern as  a  "subroutine".
-       Details  are  discussed  later.   Note  that  \g{...} (Perl syntax) and
+       an  alternative  syntax for referencing a subpattern as a "subroutine".
+       Details are discussed later.   Note  that  \g{...}  (Perl  syntax)  and
        \g<...> (Oniguruma syntax) are not synonymous. The former is a backref-
        erence; the latter is a subroutine call.


@@ -6333,43 +6346,43 @@
          \w     any "word" character
          \W     any "non-word" character


-       The  \N  escape  sequence has the same meaning as the "." metacharacter
-       when PCRE2_DOTALL is not set, but setting PCRE2_DOTALL does not  change
+       The \N escape sequence has the same meaning as  the  "."  metacharacter
+       when  PCRE2_DOTALL is not set, but setting PCRE2_DOTALL does not change
        the meaning of \N. Note that when \N is followed by an opening brace it
        has a different meaning. See the section entitled "Non-printing charac-
-       ters"  above for details. Perl also uses \N{name} to specify characters
+       ters" above for details. Perl also uses \N{name} to specify  characters
        by Unicode name; PCRE2 does not support this.


-       Each pair of lower and upper case escape sequences partitions the  com-
-       plete  set  of  characters  into two disjoint sets. Any given character
-       matches one, and only one, of each pair. The sequences can appear  both
-       inside  and outside character classes. They each match one character of
-       the appropriate type. If the current matching point is at  the  end  of
-       the  subject string, all of them fail, because there is no character to
+       Each  pair of lower and upper case escape sequences partitions the com-
+       plete set of characters into two disjoint  sets.  Any  given  character
+       matches  one, and only one, of each pair. The sequences can appear both
+       inside and outside character classes. They each match one character  of
+       the  appropriate  type.  If the current matching point is at the end of
+       the subject string, all of them fail, because there is no character  to
        match.


-       The default \s characters are HT (9), LF (10), VT  (11),  FF  (12),  CR
-       (13),  and  space  (32),  which  are  defined as white space in the "C"
+       The  default  \s  characters  are HT (9), LF (10), VT (11), FF (12), CR
+       (13), and space (32), which are defined  as  white  space  in  the  "C"
        locale. This list may vary if locale-specific matching is taking place.
-       For  example, in some locales the "non-breaking space" character (\xA0)
+       For example, in some locales the "non-breaking space" character  (\xA0)
        is recognized as white space, and in others the VT character is not.


-       A "word" character is an underscore or any character that is  a  letter
-       or  digit.   By  default,  the definition of letters and digits is con-
+       A  "word"  character is an underscore or any character that is a letter
+       or digit.  By default, the definition of letters  and  digits  is  con-
        trolled by PCRE2's low-valued character tables, and may vary if locale-
        specific matching is taking place (see "Locale support" in the pcre2api
-       page). For example, in a French locale such  as  "fr_FR"  in  Unix-like
-       systems,  or "french" in Windows, some character codes greater than 127
-       are used for accented letters, and these are then matched  by  \w.  The
+       page).  For  example,  in  a French locale such as "fr_FR" in Unix-like
+       systems, or "french" in Windows, some character codes greater than  127
+       are  used  for  accented letters, and these are then matched by \w. The
        use of locales with Unicode is discouraged.


-       By  default,  characters  whose  code points are greater than 127 never
+       By default, characters whose code points are  greater  than  127  never
        match \d, \s, or \w, and always match \D, \S, and \W, although this may
-       be  different  for characters in the range 128-255 when locale-specific
-       matching is happening.  These escape sequences  retain  their  original
-       meanings  from  before  Unicode support was available, mainly for effi-
-       ciency reasons. If the  PCRE2_UCP  option  is  set,  the  behaviour  is
-       changed  so  that  Unicode  properties  are used to determine character
+       be different for characters in the range 128-255  when  locale-specific
+       matching  is  happening.   These escape sequences retain their original
+       meanings from before Unicode support was available,  mainly  for  effi-
+       ciency  reasons.  If  the  PCRE2_UCP  option  is  set, the behaviour is
+       changed so that Unicode properties  are  used  to  determine  character
        types, as follows:


          \d  any character that matches \p{Nd} (decimal digit)
@@ -6376,15 +6389,15 @@
          \s  any character that matches \p{Z} or \h or \v
          \w  any character that matches \p{L} or \p{N}, plus underscore


-       The upper case escapes match the inverse sets of characters. Note  that
-       \d  matches  only decimal digits, whereas \w matches any Unicode digit,
+       The  upper case escapes match the inverse sets of characters. Note that
+       \d matches only decimal digits, whereas \w matches any  Unicode  digit,
        as well as any Unicode letter, and underscore. Note also that PCRE2_UCP
-       affects  \b,  and  \B  because  they are defined in terms of \w and \W.
+       affects \b, and \B because they are defined in  terms  of  \w  and  \W.
        Matching these sequences is noticeably slower when PCRE2_UCP is set.


-       The sequences \h, \H, \v, and \V, in contrast to the  other  sequences,
-       which  match  only ASCII characters by default, always match a specific
-       list of code points, whether or not PCRE2_UCP is  set.  The  horizontal
+       The  sequences  \h, \H, \v, and \V, in contrast to the other sequences,
+       which match only ASCII characters by default, always match  a  specific
+       list  of  code  points, whether or not PCRE2_UCP is set. The horizontal
        space characters are:


          U+0009     Horizontal tab (HT)
@@ -6417,36 +6430,36 @@
          U+2028     Line separator
          U+2029     Paragraph separator


-       In  8-bit,  non-UTF-8  mode,  only the characters with code points less
+       In 8-bit, non-UTF-8 mode, only the characters  with  code  points  less
        than 256 are relevant.


    Newline sequences


-       Outside a character class, by default, the escape sequence  \R  matches
-       any  Unicode newline sequence. In 8-bit non-UTF-8 mode \R is equivalent
+       Outside  a  character class, by default, the escape sequence \R matches
+       any Unicode newline sequence. In 8-bit non-UTF-8 mode \R is  equivalent
        to the following:


          (?>\r\n|\n|\x0b|\f|\r|\x85)


-       This is an example of an "atomic group", details  of  which  are  given
+       This  is  an  example  of an "atomic group", details of which are given
        below.  This particular group matches either the two-character sequence
-       CR followed by LF, or  one  of  the  single  characters  LF  (linefeed,
-       U+000A),  VT  (vertical  tab, U+000B), FF (form feed, U+000C), CR (car-
-       riage return, U+000D), or NEL (next line, U+0085). Because this  is  an
-       atomic  group,  the  two-character sequence is treated as a single unit
+       CR  followed  by  LF,  or  one  of  the single characters LF (linefeed,
+       U+000A), VT (vertical tab, U+000B), FF (form feed,  U+000C),  CR  (car-
+       riage  return,  U+000D), or NEL (next line, U+0085). Because this is an
+       atomic group, the two-character sequence is treated as  a  single  unit
        that cannot be split.


        In other modes, two additional characters whose code points are greater
        than 255 are added: LS (line separator, U+2028) and PS (paragraph sepa-
-       rator, U+2029).  Unicode support is not needed for these characters  to
+       rator,  U+2029).  Unicode support is not needed for these characters to
        be recognized.


        It is possible to restrict \R to match only CR, LF, or CRLF (instead of
-       the complete set  of  Unicode  line  endings)  by  setting  the  option
-       PCRE2_BSR_ANYCRLF  at  compile  time. (BSR is an abbrevation for "back-
+       the  complete  set  of  Unicode  line  endings)  by  setting the option
+       PCRE2_BSR_ANYCRLF at compile time. (BSR is an  abbrevation  for  "back-
        slash R".) This can be made the default when PCRE2 is built; if this is
-       the  case,  the other behaviour can be requested via the PCRE2_BSR_UNI-
-       CODE option. It is also possible to specify these settings by  starting
+       the case, the other behaviour can be requested via  the  PCRE2_BSR_UNI-
+       CODE  option. It is also possible to specify these settings by starting
        a pattern string with one of the following sequences:


          (*BSR_ANYCRLF)   CR, LF, or CRLF only
@@ -6454,26 +6467,26 @@


        These override the default and the options given to the compiling func-
        tion.  Note that these special settings, which are not Perl-compatible,
-       are  recognized only at the very start of a pattern, and that they must
-       be in upper case. If more than one of them is present, the last one  is
-       used.  They  can  be  combined with a change of newline convention; for
+       are recognized only at the very start of a pattern, and that they  must
+       be  in upper case. If more than one of them is present, the last one is
+       used. They can be combined with a change  of  newline  convention;  for
        example, a pattern can start with:


          (*ANY)(*BSR_ANYCRLF)


-       They can also be combined with the (*UTF) or (*UCP) special  sequences.
-       Inside  a  character  class,  \R  is  treated as an unrecognized escape
+       They  can also be combined with the (*UTF) or (*UCP) special sequences.
+       Inside a character class, \R  is  treated  as  an  unrecognized  escape
        sequence, and causes an error.


    Unicode character properties


-       When PCRE2 is built with Unicode support  (the  default),  three  addi-
-       tional  escape sequences that match characters with specific properties
-       are available. In 8-bit non-UTF-8 mode, these sequences are  of  course
-       limited  to testing characters whose code points are less than 256, but
+       When  PCRE2  is  built  with Unicode support (the default), three addi-
+       tional escape sequences that match characters with specific  properties
+       are  available.  In 8-bit non-UTF-8 mode, these sequences are of course
+       limited to testing characters whose code points are less than 256,  but
        they do work in this mode.  In 32-bit non-UTF mode, code points greater
-       than  0x10ffff  (the  Unicode  limit) may be encountered. These are all
-       treated as being in the Common script and with an unassigned type.  The
+       than 0x10ffff (the Unicode limit) may be  encountered.  These  are  all
+       treated  as being in the Common script and with an unassigned type. The
        extra escape sequences are:


          \p{xx}   a character with the xx property
@@ -6480,56 +6493,56 @@
          \P{xx}   a character without the xx property
          \X       a Unicode extended grapheme cluster


-       The  property  names represented by xx above are limited to the Unicode
+       The property names represented by xx above are limited to  the  Unicode
        script names, the general category properties, "Any", which matches any
        character  (including  newline),  and  some  special  PCRE2  properties
-       (described in the next section).  Other Perl properties such as  "InMu-
-       sicalSymbols"  are  not supported by PCRE2.  Note that \P{Any} does not
+       (described  in the next section).  Other Perl properties such as "InMu-
+       sicalSymbols" are not supported by PCRE2.  Note that \P{Any}  does  not
        match any characters, so always causes a match failure.


        Sets of Unicode characters are defined as belonging to certain scripts.
-       A  character from one of these sets can be matched using a script name.
+       A character from one of these sets can be matched using a script  name.
        For example:


          \p{Greek}
          \P{Han}


-       Those that are not part of an identified script are lumped together  as
+       Those  that are not part of an identified script are lumped together as
        "Common". The current list of scripts is:


-       Adlam,  Ahom,  Anatolian_Hieroglyphs,  Arabic, Armenian, Avestan, Bali-
-       nese, Bamum, Bassa_Vah, Batak, Bengali,  Bhaiksuki,  Bopomofo,  Brahmi,
-       Braille,  Buginese, Buhid, Canadian_Aboriginal, Carian, Caucasian_Alba-
-       nian, Chakma,  Cham,  Cherokee,  Common,  Coptic,  Cuneiform,  Cypriot,
-       Cyrillic,  Deseret,  Devanagari, Dogra, Duployan, Egyptian_Hieroglyphs,
-       Elbasan,  Ethiopic,  Georgian,  Glagolitic,  Gothic,  Grantha,   Greek,
-       Gujarati,   Gunjala_Gondi,   Gurmukhi,  Han,  Hangul,  Hanifi_Rohingya,
-       Hanunoo,  Hatran,  Hebrew,   Hiragana,   Imperial_Aramaic,   Inherited,
-       Inscriptional_Pahlavi,  Inscriptional_Parthian,  Javanese, Kaithi, Kan-
-       nada, Katakana, Kayah_Li, Kharoshthi, Khmer,  Khojki,  Khudawadi,  Lao,
-       Latin,  Lepcha,  Limbu, Linear_A, Linear_B, Lisu, Lycian, Lydian, Maha-
-       jani, Makasar, Malayalam, Mandaic, Manichaean, Marchen,  Masaram_Gondi,
+       Adlam, Ahom, Anatolian_Hieroglyphs, Arabic,  Armenian,  Avestan,  Bali-
+       nese,  Bamum,  Bassa_Vah,  Batak, Bengali, Bhaiksuki, Bopomofo, Brahmi,
+       Braille, Buginese, Buhid, Canadian_Aboriginal, Carian,  Caucasian_Alba-
+       nian,  Chakma,  Cham,  Cherokee,  Common,  Coptic,  Cuneiform, Cypriot,
+       Cyrillic, Deseret, Devanagari, Dogra,  Duployan,  Egyptian_Hieroglyphs,
+       Elbasan,   Ethiopic,  Georgian,  Glagolitic,  Gothic,  Grantha,  Greek,
+       Gujarati,  Gunjala_Gondi,  Gurmukhi,  Han,   Hangul,   Hanifi_Rohingya,
+       Hanunoo,   Hatran,   Hebrew,   Hiragana,  Imperial_Aramaic,  Inherited,
+       Inscriptional_Pahlavi, Inscriptional_Parthian, Javanese,  Kaithi,  Kan-
+       nada,  Katakana,  Kayah_Li,  Kharoshthi, Khmer, Khojki, Khudawadi, Lao,
+       Latin, Lepcha, Limbu, Linear_A, Linear_B, Lisu, Lycian,  Lydian,  Maha-
+       jani,  Makasar, Malayalam, Mandaic, Manichaean, Marchen, Masaram_Gondi,
        Medefaidrin,     Meetei_Mayek,     Mende_Kikakui,     Meroitic_Cursive,
-       Meroitic_Hieroglyphs, Miao, Modi,  Mongolian,  Mro,  Multani,  Myanmar,
-       Nabataean,  New_Tai_Lue, Newa, Nko, Nushu, Ogham, Ol_Chiki, Old_Hungar-
-       ian, Old_Italic, Old_North_Arabian, Old_Permic,  Old_Persian,  Old_Sog-
-       dian,    Old_South_Arabian,    Old_Turkic,   Oriya,   Osage,   Osmanya,
+       Meroitic_Hieroglyphs,  Miao,  Modi,  Mongolian,  Mro, Multani, Myanmar,
+       Nabataean, New_Tai_Lue, Newa, Nko, Nushu, Ogham, Ol_Chiki,  Old_Hungar-
+       ian,  Old_Italic,  Old_North_Arabian, Old_Permic, Old_Persian, Old_Sog-
+       dian,   Old_South_Arabian,   Old_Turkic,   Oriya,    Osage,    Osmanya,
        Pahawh_Hmong,    Palmyrene,    Pau_Cin_Hau,    Phags_Pa,    Phoenician,
-       Psalter_Pahlavi,  Rejang,  Runic,  Samaritan, Saurashtra, Sharada, Sha-
-       vian, Siddham, SignWriting, Sinhala,  Sogdian,  Sora_Sompeng,  Soyombo,
-       Sundanese,  Syloti_Nagri,  Syriac, Tagalog, Tagbanwa, Tai_Le, Tai_Tham,
-       Tai_Viet, Takri, Tamil, Tangut, Telugu, Thaana,  Thai,  Tibetan,  Tifi-
+       Psalter_Pahlavi, Rejang, Runic, Samaritan,  Saurashtra,  Sharada,  Sha-
+       vian,  Siddham,  SignWriting,  Sinhala, Sogdian, Sora_Sompeng, Soyombo,
+       Sundanese, Syloti_Nagri, Syriac, Tagalog, Tagbanwa,  Tai_Le,  Tai_Tham,
+       Tai_Viet,  Takri,  Tamil,  Tangut, Telugu, Thaana, Thai, Tibetan, Tifi-
        nagh, Tirhuta, Ugaritic, Vai, Warang_Citi, Yi, Zanabazar_Square.


        Each character has exactly one Unicode general category property, spec-
-       ified by a two-letter abbreviation. For compatibility with Perl,  nega-
-       tion  can  be  specified  by including a circumflex between the opening
-       brace and the property name.  For  example,  \p{^Lu}  is  the  same  as
+       ified  by a two-letter abbreviation. For compatibility with Perl, nega-
+       tion can be specified by including a  circumflex  between  the  opening
+       brace  and  the  property  name.  For  example,  \p{^Lu} is the same as
        \P{Lu}.


        If only one letter is specified with \p or \P, it includes all the gen-
-       eral category properties that start with that letter. In this case,  in
-       the  absence of negation, the curly brackets in the escape sequence are
+       eral  category properties that start with that letter. In this case, in
+       the absence of negation, the curly brackets in the escape sequence  are
        optional; these two examples have the same effect:


          \p{L}
@@ -6581,18 +6594,18 @@
          Zp    Paragraph separator
          Zs    Space separator


-       The special property L& is also supported: it matches a character  that
-       has  the  Lu,  Ll, or Lt property, in other words, a letter that is not
+       The  special property L& is also supported: it matches a character that
+       has the Lu, Ll, or Lt property, in other words, a letter  that  is  not
        classified as a modifier or "other".


-       The Cs (Surrogate) property applies only to  characters  in  the  range
-       U+D800  to U+DFFF. Such characters are not valid in Unicode strings and
-       so cannot be tested by PCRE2, unless UTF  validity  checking  has  been
-       turned  off  (see  the discussion of PCRE2_NO_UTF_CHECK in the pcre2api
+       The  Cs  (Surrogate)  property  applies only to characters in the range
+       U+D800 to U+DFFF. Such characters are not valid in Unicode strings  and
+       so  cannot  be  tested  by PCRE2, unless UTF validity checking has been
+       turned off (see the discussion of PCRE2_NO_UTF_CHECK  in  the  pcre2api
        page). Perl does not support the Cs property.


-       The long synonyms for  property  names  that  Perl  supports  (such  as
-       \p{Letter})  are  not supported by PCRE2, nor is it permitted to prefix
+       The  long  synonyms  for  property  names  that  Perl supports (such as
+       \p{Letter}) are not supported by PCRE2, nor is it permitted  to  prefix
        any of these properties with "Is".


        No character that is in the Unicode table has the Cn (unassigned) prop-
@@ -6599,47 +6612,47 @@
        erty.  Instead, this property is assumed for any code point that is not
        in the Unicode table.


-       Specifying caseless matching does not affect  these  escape  sequences.
-       For  example,  \p{Lu}  always  matches only upper case letters. This is
+       Specifying  caseless  matching  does not affect these escape sequences.
+       For example, \p{Lu} always matches only upper  case  letters.  This  is
        different from the behaviour of current versions of Perl.


-       Matching characters by Unicode property is not fast, because PCRE2  has
-       to  do  a  multistage table lookup in order to find a character's prop-
+       Matching  characters by Unicode property is not fast, because PCRE2 has
+       to do a multistage table lookup in order to find  a  character's  prop-
        erty. That is why the traditional escape sequences such as \d and \w do
-       not  use  Unicode  properties  in PCRE2 by default, though you can make
-       them do so by setting the PCRE2_UCP option or by starting  the  pattern
+       not use Unicode properties in PCRE2 by default,  though  you  can  make
+       them  do  so by setting the PCRE2_UCP option or by starting the pattern
        with (*UCP).


    Extended grapheme clusters


-       The  \X  escape  matches  any number of Unicode characters that form an
+       The \X escape matches any number of Unicode  characters  that  form  an
        "extended grapheme cluster", and treats the sequence as an atomic group
-       (see  below).  Unicode supports various kinds of composite character by
-       giving each character a grapheme breaking property,  and  having  rules
+       (see below).  Unicode supports various kinds of composite character  by
+       giving  each  character  a grapheme breaking property, and having rules
        that use these properties to define the boundaries of extended grapheme
-       clusters. The rules are defined in Unicode Standard Annex 29,  "Unicode
-       Text  Segmentation".  Unicode 11.0.0 abandoned the use of some previous
-       properties that had been used for emojis.  Instead it introduced  vari-
-       ous  emoji-specific  properties.  PCRE2  uses  only the Extended Picto-
+       clusters.  The rules are defined in Unicode Standard Annex 29, "Unicode
+       Text Segmentation". Unicode 11.0.0 abandoned the use of  some  previous
+       properties  that had been used for emojis.  Instead it introduced vari-
+       ous emoji-specific properties. PCRE2  uses  only  the  Extended  Picto-
        graphic property.


-       \X always matches at least one character. Then it  decides  whether  to
+       \X  always  matches  at least one character. Then it decides whether to
        add additional characters according to the following rules for ending a
        cluster:


        1. End at the end of the subject string.


-       2. Do not end between CR and LF; otherwise end after any control  char-
+       2.  Do not end between CR and LF; otherwise end after any control char-
        acter.


-       3.  Do  not  break  Hangul (a Korean script) syllable sequences. Hangul
-       characters are of five types: L, V, T, LV, and LVT. An L character  may
-       be  followed by an L, V, LV, or LVT character; an LV or V character may
+       3. Do not break Hangul (a Korean  script)  syllable  sequences.  Hangul
+       characters  are of five types: L, V, T, LV, and LVT. An L character may
+       be followed by an L, V, LV, or LVT character; an LV or V character  may
        be followed by a V or T character; an LVT or T character may be follwed
        only by a T character.


-       4.  Do  not  end  before  extending  characters or spacing marks or the
-       "zero-width joiner" character.  Characters  with  the  "mark"  property
+       4. Do not end before extending  characters  or  spacing  marks  or  the
+       "zero-width  joiner"  character.  Characters  with  the "mark" property
        always have the "extend" grapheme breaking property.


        5. Do not end after prepend characters.
@@ -6646,11 +6659,11 @@


        6. Do not break within emoji modifier sequences or emoji zwj sequences.
        That is, do not break between characters with the Extended_Pictographic
-       property.   Extend  and  ZWJ characters are allowed between the charac-
+       property.  Extend and ZWJ characters are allowed  between  the  charac-
        ters.


-       7. Do not break within emoji flag sequences.  That  is,  do  not  break
-       between  regional  indicator (RI) characters if there are an odd number
+       7.  Do  not  break  within  emoji flag sequences. That is, do not break
+       between regional indicator (RI) characters if there are an  odd  number
        of RI characters before the break point.


        8. Otherwise, end the cluster.
@@ -6657,10 +6670,10 @@


    PCRE2's additional properties


-       As well as the standard Unicode properties described above, PCRE2  sup-
-       ports  four  more  that  make it possible to convert traditional escape
+       As  well as the standard Unicode properties described above, PCRE2 sup-
+       ports four more that make it possible  to  convert  traditional  escape
        sequences such as \w and \s to use Unicode properties. PCRE2 uses these
-       non-standard,  non-Perl  properties  internally  when PCRE2_UCP is set.
+       non-standard, non-Perl properties internally  when  PCRE2_UCP  is  set.
        However, they may also be used explicitly. These properties are:


          Xan   Any alphanumeric character
@@ -6668,42 +6681,42 @@
          Xsp   Any Perl space character
          Xwd   Any Perl "word" character


-       Xan matches characters that have either the L (letter) or the  N  (num-
-       ber)  property. Xps matches the characters tab, linefeed, vertical tab,
-       form feed, or carriage return, and any other character that has  the  Z
-       (separator)  property.   Xsp  is  the  same as Xps; in PCRE1 it used to
-       exclude vertical tab, for Perl compatibility,  but  Perl  changed.  Xwd
+       Xan  matches  characters that have either the L (letter) or the N (num-
+       ber) property. Xps matches the characters tab, linefeed, vertical  tab,
+       form  feed,  or carriage return, and any other character that has the Z
+       (separator) property.  Xsp is the same as Xps;  in  PCRE1  it  used  to
+       exclude  vertical  tab,  for  Perl compatibility, but Perl changed. Xwd
        matches the same characters as Xan, plus underscore.


-       There  is another non-standard property, Xuc, which matches any charac-
-       ter that can be represented by a Universal Character Name  in  C++  and
-       other  programming  languages.  These are the characters $, @, ` (grave
-       accent), and all characters with Unicode code points  greater  than  or
-       equal  to U+00A0, except for the surrogates U+D800 to U+DFFF. Note that
-       most base (ASCII) characters are excluded. (Universal  Character  Names
-       are  of  the  form \uHHHH or \UHHHHHHHH where H is a hexadecimal digit.
+       There is another non-standard property, Xuc, which matches any  charac-
+       ter  that  can  be represented by a Universal Character Name in C++ and
+       other programming languages. These are the characters $,  @,  `  (grave
+       accent),  and  all  characters with Unicode code points greater than or
+       equal to U+00A0, except for the surrogates U+D800 to U+DFFF. Note  that
+       most  base  (ASCII) characters are excluded. (Universal Character Names
+       are of the form \uHHHH or \UHHHHHHHH where H is  a  hexadecimal  digit.
        Note that the Xuc property does not match these sequences but the char-
        acters that they represent.)


    Resetting the match start


-       In  normal  use,  the  escape sequence \K causes any previously matched
-       characters not to be included in the final  matched  sequence  that  is
+       In normal use, the escape sequence \K  causes  any  previously  matched
+       characters  not  to  be  included in the final matched sequence that is
        returned. For example, the pattern:


          foo\Kbar


-       matches  "foobar",  but  reports that it has matched "bar". \K does not
+       matches "foobar", but reports that it has matched "bar".  \K  does  not
        interact with anchoring in any way. The pattern:


          ^foo\Kbar


-       matches only when the subject begins  with  "foobar"  (in  single  line
-       mode),  though  it again reports the matched string as "bar". This fea-
-       ture is similar to a lookbehind assertion (described below).   However,
-       in  this  case,  the part of the subject before the real match does not
-       have to be of fixed length, as lookbehind assertions do. The use of  \K
-       does  not interfere with the setting of captured substrings.  For exam-
+       matches  only  when  the  subject  begins with "foobar" (in single line
+       mode), though it again reports the matched string as "bar".  This  fea-
+       ture  is similar to a lookbehind assertion (described below).  However,
+       in this case, the part of the subject before the real  match  does  not
+       have  to be of fixed length, as lookbehind assertions do. The use of \K
+       does not interfere with the setting of captured substrings.  For  exam-
        ple, when the pattern


          (foo)\Kbar
@@ -6710,27 +6723,27 @@


        matches "foobar", the first substring is still set to "foo".


-       Perl documents that the use  of  \K  within  assertions  is  "not  well
-       defined".  In  PCRE2,  \K  is acted upon when it occurs inside positive
-       assertions, but is ignored in negative assertions.  Note  that  when  a
-       pattern  such  as (?=ab\K) matches, the reported start of the match can
-       be greater than the end of the match. Using \K in a  lookbehind  asser-
-       tion  at the start of a pattern can also lead to odd effects. For exam-
+       Perl  documents  that  the  use  of  \K  within assertions is "not well
+       defined". In PCRE2, \K is acted upon when  it  occurs  inside  positive
+       assertions,  but  is  ignored  in negative assertions. Note that when a
+       pattern such as (?=ab\K) matches, the reported start of the  match  can
+       be  greater  than the end of the match. Using \K in a lookbehind asser-
+       tion at the start of a pattern can also lead to odd effects. For  exam-
        ple, consider this pattern:


          (?<=\Kfoo)bar


-       If the subject is "foobar", a call to  pcre2_match()  with  a  starting
-       offset  of 3 succeeds and reports the matching string as "foobar", that
-       is, the start of the reported match is earlier  than  where  the  match
+       If  the  subject  is  "foobar", a call to pcre2_match() with a starting
+       offset of 3 succeeds and reports the matching string as "foobar",  that
+       is,  the  start  of  the reported match is earlier than where the match
        started.


    Simple assertions


-       The  final use of backslash is for certain simple assertions. An asser-
-       tion specifies a condition that has to be met at a particular point  in
-       a  match, without consuming any characters from the subject string. The
-       use of subpatterns for more complicated assertions is described  below.
+       The final use of backslash is for certain simple assertions. An  asser-
+       tion  specifies a condition that has to be met at a particular point in
+       a match, without consuming any characters from the subject string.  The
+       use  of subpatterns for more complicated assertions is described below.
        The backslashed assertions are:


          \b     matches at a word boundary
@@ -6741,47 +6754,47 @@
          \z     matches only at the end of the subject
          \G     matches at the first matching position in the subject


-       Inside  a  character  class, \b has a different meaning; it matches the
-       backspace character. If any other of  these  assertions  appears  in  a
+       Inside a character class, \b has a different meaning;  it  matches  the
+       backspace  character.  If  any  other  of these assertions appears in a
        character class, an "invalid escape sequence" error is generated.


-       A  word  boundary is a position in the subject string where the current
-       character and the previous character do not both match \w or  \W  (i.e.
-       one  matches  \w  and the other matches \W), or the start or end of the
-       string if the first or last character matches \w,  respectively.  In  a
-       UTF  mode,  the  meanings  of  \w  and \W can be changed by setting the
+       A word boundary is a position in the subject string where  the  current
+       character  and  the previous character do not both match \w or \W (i.e.
+       one matches \w and the other matches \W), or the start or  end  of  the
+       string  if  the  first or last character matches \w, respectively. In a
+       UTF mode, the meanings of \w and \W  can  be  changed  by  setting  the
        PCRE2_UCP option. When this is done, it also affects \b and \B. Neither
-       PCRE2  nor Perl has a separate "start of word" or "end of word" metase-
-       quence. However, whatever follows \b normally determines which  it  is.
+       PCRE2 nor Perl has a separate "start of word" or "end of word"  metase-
+       quence.  However,  whatever follows \b normally determines which it is.
        For example, the fragment \ba matches "a" at the start of a word.


-       The  \A,  \Z,  and \z assertions differ from the traditional circumflex
+       The \A, \Z, and \z assertions differ from  the  traditional  circumflex
        and dollar (described in the next section) in that they only ever match
-       at  the  very start and end of the subject string, whatever options are
-       set. Thus, they are independent of multiline mode. These  three  asser-
-       tions  are  not  affected  by the PCRE2_NOTBOL or PCRE2_NOTEOL options,
-       which affect only the behaviour of the circumflex and dollar  metachar-
-       acters.  However,  if the startoffset argument of pcre2_match() is non-
-       zero, indicating that matching is to start at a point  other  than  the
-       beginning  of  the subject, \A can never match.  The difference between
-       \Z and \z is that \Z matches before a newline at the end of the  string
+       at the very start and end of the subject string, whatever  options  are
+       set.  Thus,  they are independent of multiline mode. These three asser-
+       tions are not affected by the  PCRE2_NOTBOL  or  PCRE2_NOTEOL  options,
+       which  affect only the behaviour of the circumflex and dollar metachar-
+       acters. However, if the startoffset argument of pcre2_match()  is  non-
+       zero,  indicating  that  matching is to start at a point other than the
+       beginning of the subject, \A can never match.  The  difference  between
+       \Z  and \z is that \Z matches before a newline at the end of the string
        as well as at the very end, whereas \z matches only at the end.


-       The  \G assertion is true only when the current matching position is at
-       the start point of the matching process, as specified by the  startoff-
-       set  argument  of  pcre2_match().  It differs from \A when the value of
-       startoffset is non-zero. By calling pcre2_match() multiple  times  with
-       appropriate  arguments,  you  can  mimic Perl's /g option, and it is in
+       The \G assertion is true only when the current matching position is  at
+       the  start point of the matching process, as specified by the startoff-
+       set argument of pcre2_match(). It differs from \A  when  the  value  of
+       startoffset  is  non-zero. By calling pcre2_match() multiple times with
+       appropriate arguments, you can mimic Perl's /g option,  and  it  is  in
        this kind of implementation where \G can be useful.


-       Note, however, that PCRE2's implementation of \G,  being  true  at  the
-       starting  character  of  the matching process, is subtly different from
-       Perl's, which defines it as true at the end of the previous  match.  In
-       Perl,  these  can  be  different when the previously matched string was
+       Note,  however,  that  PCRE2's  implementation of \G, being true at the
+       starting character of the matching process, is  subtly  different  from
+       Perl's,  which  defines it as true at the end of the previous match. In
+       Perl, these can be different when the  previously  matched  string  was
        empty. Because PCRE2 does just one match at a time, it cannot reproduce
        this behaviour.


-       If  all  the alternatives of a pattern begin with \G, the expression is
+       If all the alternatives of a pattern begin with \G, the  expression  is
        anchored to the starting match position, and the "anchored" flag is set
        in the compiled regular expression.


@@ -6788,70 +6801,70 @@

CIRCUMFLEX AND DOLLAR

-       The  circumflex  and  dollar  metacharacters are zero-width assertions.
-       That is, they test for a particular condition being true  without  con-
+       The circumflex and dollar  metacharacters  are  zero-width  assertions.
+       That  is,  they test for a particular condition being true without con-
        suming any characters from the subject string. These two metacharacters
-       are concerned with matching the starts and ends of lines. If  the  new-
-       line  convention is set so that only the two-character sequence CRLF is
-       recognized as a newline, isolated CR and LF characters are  treated  as
+       are  concerned  with matching the starts and ends of lines. If the new-
+       line convention is set so that only the two-character sequence CRLF  is
+       recognized  as  a newline, isolated CR and LF characters are treated as
        ordinary data characters, and are not recognized as newlines.


        Outside a character class, in the default matching mode, the circumflex
-       character is an assertion that is true only  if  the  current  matching
-       point  is  at the start of the subject string. If the startoffset argu-
-       ment of pcre2_match() is non-zero, or if PCRE2_NOTBOL is  set,  circum-
-       flex  can  never match if the PCRE2_MULTILINE option is unset. Inside a
-       character class, circumflex has  an  entirely  different  meaning  (see
+       character  is  an  assertion  that is true only if the current matching
+       point is at the start of the subject string. If the  startoffset  argu-
+       ment  of  pcre2_match() is non-zero, or if PCRE2_NOTBOL is set, circum-
+       flex can never match if the PCRE2_MULTILINE option is unset.  Inside  a
+       character  class,  circumflex  has  an  entirely different meaning (see
        below).


-       Circumflex  need  not be the first character of the pattern if a number
-       of alternatives are involved, but it should be the first thing in  each
-       alternative  in  which  it appears if the pattern is ever to match that
-       branch. If all possible alternatives start with a circumflex, that  is,
-       if  the  pattern  is constrained to match only at the start of the sub-
-       ject, it is said to be an "anchored" pattern.  (There  are  also  other
+       Circumflex need not be the first character of the pattern if  a  number
+       of  alternatives are involved, but it should be the first thing in each
+       alternative in which it appears if the pattern is ever  to  match  that
+       branch.  If all possible alternatives start with a circumflex, that is,
+       if the pattern is constrained to match only at the start  of  the  sub-
+       ject,  it  is  said  to be an "anchored" pattern. (There are also other
        constructs that can cause a pattern to be anchored.)


-       The  dollar  character is an assertion that is true only if the current
-       matching point is at the end of  the  subject  string,  or  immediately
-       before  a  newline  at  the  end  of  the  string  (by default), unless
+       The dollar character is an assertion that is true only if  the  current
+       matching  point  is  at  the  end of the subject string, or immediately
+       before a newline  at  the  end  of  the  string  (by  default),  unless
        PCRE2_NOTEOL is set. Note, however, that it does not actually match the
        newline. Dollar need not be the last character of the pattern if a num-
        ber of alternatives are involved, but it should be the last item in any
-       branch  in which it appears. Dollar has no special meaning in a charac-
+       branch in which it appears. Dollar has no special meaning in a  charac-
        ter class.


-       The meaning of dollar can be changed so that it  matches  only  at  the
-       very  end  of the string, by setting the PCRE2_DOLLAR_ENDONLY option at
+       The  meaning  of  dollar  can be changed so that it matches only at the
+       very end of the string, by setting the PCRE2_DOLLAR_ENDONLY  option  at
        compile time. This does not affect the \Z assertion.


        The meanings of the circumflex and dollar metacharacters are changed if
-       the  PCRE2_MULTILINE  option  is  set.  When this is the case, a dollar
-       character matches before any newlines in the string, as well as at  the
-       very  end, and a circumflex matches immediately after internal newlines
-       as well as at the start of the subject string. It does not match  after
-       a  newline  that ends the string, for compatibility with Perl. However,
+       the PCRE2_MULTILINE option is set. When this  is  the  case,  a  dollar
+       character  matches before any newlines in the string, as well as at the
+       very end, and a circumflex matches immediately after internal  newlines
+       as  well as at the start of the subject string. It does not match after
+       a newline that ends the string, for compatibility with  Perl.  However,
        this can be changed by setting the PCRE2_ALT_CIRCUMFLEX option.


-       For example, the pattern /^abc$/ matches the subject string  "def\nabc"
-       (where  \n  represents a newline) in multiline mode, but not otherwise.
-       Consequently, patterns that are anchored in single  line  mode  because
-       all  branches  start  with  ^ are not anchored in multiline mode, and a
-       match for circumflex is  possible  when  the  startoffset  argument  of
-       pcre2_match()  is  non-zero. The PCRE2_DOLLAR_ENDONLY option is ignored
+       For  example, the pattern /^abc$/ matches the subject string "def\nabc"
+       (where \n represents a newline) in multiline mode, but  not  otherwise.
+       Consequently,  patterns  that  are anchored in single line mode because
+       all branches start with ^ are not anchored in  multiline  mode,  and  a
+       match  for  circumflex  is  possible  when  the startoffset argument of
+       pcre2_match() is non-zero. The PCRE2_DOLLAR_ENDONLY option  is  ignored
        if PCRE2_MULTILINE is set.


-       When the newline convention (see "Newline  conventions"  below)  recog-
-       nizes  the two-character sequence CRLF as a newline, this is preferred,
-       even if the single characters CR and LF are  also  recognized  as  new-
-       lines.  For  example,  if  the newline convention is "any", a multiline
-       mode circumflex matches before "xyz" in the string "abc\r\nxyz"  rather
-       than  after  CR, even though CR on its own is a valid newline. (It also
+       When  the  newline  convention (see "Newline conventions" below) recog-
+       nizes the two-character sequence CRLF as a newline, this is  preferred,
+       even  if  the  single  characters CR and LF are also recognized as new-
+       lines. For example, if the newline convention  is  "any",  a  multiline
+       mode  circumflex matches before "xyz" in the string "abc\r\nxyz" rather
+       than after CR, even though CR on its own is a valid newline.  (It  also
        matches at the very start of the string, of course.)


-       Note that the sequences \A, \Z, and \z can be used to match  the  start
-       and  end of the subject in both modes, and if all branches of a pattern
-       start with \A it is always anchored, whether or not PCRE2_MULTILINE  is
+       Note  that  the sequences \A, \Z, and \z can be used to match the start
+       and end of the subject in both modes, and if all branches of a  pattern
+       start  with \A it is always anchored, whether or not PCRE2_MULTILINE is
        set.



@@ -6858,73 +6871,73 @@
FULL STOP (PERIOD, DOT) AND \N

        Outside a character class, a dot in the pattern matches any one charac-
-       ter in the subject string except (by default) a character  that  signi-
+       ter  in  the subject string except (by default) a character that signi-
        fies the end of a line.


-       When  a line ending is defined as a single character, dot never matches
-       that character; when the two-character sequence CRLF is used, dot  does
-       not  match  CR  if  it  is immediately followed by LF, but otherwise it
-       matches all characters (including isolated CRs and LFs). When any  Uni-
-       code  line endings are being recognized, dot does not match CR or LF or
+       When a line ending is defined as a single character, dot never  matches
+       that  character; when the two-character sequence CRLF is used, dot does
+       not match CR if it is immediately followed  by  LF,  but  otherwise  it
+       matches  all characters (including isolated CRs and LFs). When any Uni-
+       code line endings are being recognized, dot does not match CR or LF  or
        any of the other line ending characters.


-       The behaviour of dot with regard to newlines can  be  changed.  If  the
-       PCRE2_DOTALL  option  is  set, a dot matches any one character, without
-       exception.  If the two-character sequence CRLF is present in  the  sub-
+       The  behaviour  of  dot  with regard to newlines can be changed. If the
+       PCRE2_DOTALL option is set, a dot matches any  one  character,  without
+       exception.   If  the two-character sequence CRLF is present in the sub-
        ject string, it takes two dots to match it.


-       The  handling of dot is entirely independent of the handling of circum-
-       flex and dollar, the only relationship being  that  they  both  involve
+       The handling of dot is entirely independent of the handling of  circum-
+       flex  and  dollar,  the  only relationship being that they both involve
        newlines. Dot has no special meaning in a character class.


-       The  escape  sequence  \N when not followed by an opening brace behaves
-       like a dot, except that it is not affected by the PCRE2_DOTALL  option.
-       In  other words, it matches any character except one that signifies the
+       The escape sequence \N when not followed by an  opening  brace  behaves
+       like  a dot, except that it is not affected by the PCRE2_DOTALL option.
+       In other words, it matches any character except one that signifies  the
        end of a line.


        When \N is followed by an opening brace it has a different meaning. See
-       the  section entitled "Non-printing characters" above for details. Perl
-       also uses \N{name} to specify characters by Unicode  name;  PCRE2  does
+       the section entitled "Non-printing characters" above for details.  Perl
+       also  uses  \N{name}  to specify characters by Unicode name; PCRE2 does
        not support this.



MATCHING A SINGLE CODE UNIT

-       Outside  a character class, the escape sequence \C matches any one code
-       unit, whether or not a UTF mode is set. In the 8-bit library, one  code
-       unit  is  one  byte;  in the 16-bit library it is a 16-bit unit; in the
-       32-bit library it is a 32-bit unit. Unlike a  dot,  \C  always  matches
-       line-ending  characters.  The  feature  is provided in Perl in order to
+       Outside a character class, the escape sequence \C matches any one  code
+       unit,  whether or not a UTF mode is set. In the 8-bit library, one code
+       unit is one byte; in the 16-bit library it is a  16-bit  unit;  in  the
+       32-bit  library  it  is  a 32-bit unit. Unlike a dot, \C always matches
+       line-ending characters. The feature is provided in  Perl  in  order  to
        match individual bytes in UTF-8 mode, but it is unclear how it can use-
        fully be used.


-       Because  \C  breaks  up characters into individual code units, matching
-       one unit with \C in UTF-8 or UTF-16 mode means that  the  rest  of  the
-       string  may  start  with  a malformed UTF character. This has undefined
+       Because \C breaks up characters into individual  code  units,  matching
+       one  unit  with  \C  in UTF-8 or UTF-16 mode means that the rest of the
+       string may start with a malformed UTF  character.  This  has  undefined
        results, because PCRE2 assumes that it is matching character by charac-
-       ter  in  a  valid UTF string (by default it checks the subject string's
-       validity at the  start  of  processing  unless  the  PCRE2_NO_UTF_CHECK
+       ter in a valid UTF string (by default it checks  the  subject  string's
+       validity  at  the  start  of  processing  unless the PCRE2_NO_UTF_CHECK
        option is used).


-       An   application   can   lock   out  the  use  of  \C  by  setting  the
-       PCRE2_NEVER_BACKSLASH_C option when compiling a  pattern.  It  is  also
+       An  application  can  lock  out  the  use  of   \C   by   setting   the
+       PCRE2_NEVER_BACKSLASH_C  option  when  compiling  a pattern. It is also
        possible to build PCRE2 with the use of \C permanently disabled.


-       PCRE2  does  not allow \C to appear in lookbehind assertions (described
-       below) in UTF-8 or UTF-16 modes, because this would make it  impossible
-       to  calculate  the  length  of  the lookbehind. Neither the alternative
+       PCRE2 does not allow \C to appear in lookbehind  assertions  (described
+       below)  in UTF-8 or UTF-16 modes, because this would make it impossible
+       to calculate the length of  the  lookbehind.  Neither  the  alternative
        matching function pcre2_dfa_match() nor the JIT optimizer support \C in
        these UTF modes.  The former gives a match-time error; the latter fails
        to optimize and so the match is always run using the interpreter.


-       In the 32-bit library,  however,  \C  is  always  supported  (when  not
-       explicitly  locked  out)  because it always matches a single code unit,
+       In  the  32-bit  library,  however,  \C  is  always supported (when not
+       explicitly locked out) because it always matches a  single  code  unit,
        whether or not UTF-32 is specified.


        In general, the \C escape sequence is best avoided. However, one way of
-       using  it  that avoids the problem of malformed UTF-8 or UTF-16 charac-
-       ters is to use a lookahead to check the length of the  next  character,
-       as  in  this  pattern,  which could be used with a UTF-8 string (ignore
+       using it that avoids the problem of malformed UTF-8 or  UTF-16  charac-
+       ters  is  to use a lookahead to check the length of the next character,
+       as in this pattern, which could be used with  a  UTF-8  string  (ignore
        white space and line breaks):


          (?| (?=[\x00-\x7f])(\C) |
@@ -6932,10 +6945,10 @@
              (?=[\x{800}-\x{ffff}])(\C)(\C)(\C) |
              (?=[\x{10000}-\x{1fffff}])(\C)(\C)(\C)(\C))


-       In this example, a group that starts  with  (?|  resets  the  capturing
+       In  this  example,  a  group  that starts with (?| resets the capturing
        parentheses numbers in each alternative (see "Duplicate Subpattern Num-
        bers" below). The assertions at the start of each branch check the next
-       UTF-8  character  for  values  whose encoding uses 1, 2, 3, or 4 bytes,
+       UTF-8 character for values whose encoding uses 1, 2,  3,  or  4  bytes,
        respectively. The character's individual bytes are then captured by the
        appropriate number of \C groups.


@@ -6944,115 +6957,115 @@

        An opening square bracket introduces a character class, terminated by a
        closing square bracket. A closing square bracket on its own is not spe-
-       cial  by  default.  If a closing square bracket is required as a member
+       cial by default.  If a closing square bracket is required as  a  member
        of the class, it should be the first data character in the class (after
-       an  initial  circumflex,  if present) or escaped with a backslash. This
-       means that, by default, an empty class cannot be defined.  However,  if
-       the  PCRE2_ALLOW_EMPTY_CLASS option is set, a closing square bracket at
+       an initial circumflex, if present) or escaped with  a  backslash.  This
+       means  that,  by default, an empty class cannot be defined. However, if
+       the PCRE2_ALLOW_EMPTY_CLASS option is set, a closing square bracket  at
        the start does end the (empty) class.


-       A character class matches a single character in the subject. A  matched
+       A  character class matches a single character in the subject. A matched
        character must be in the set of characters defined by the class, unless
-       the first character in the class definition is a circumflex,  in  which
+       the  first  character in the class definition is a circumflex, in which
        case the subject character must not be in the set defined by the class.
-       If a circumflex is actually required as a member of the  class,  ensure
+       If  a  circumflex is actually required as a member of the class, ensure
        it is not the first character, or escape it with a backslash.


-       For  example, the character class [aeiou] matches any lower case vowel,
-       while [^aeiou] matches any character that is not a  lower  case  vowel.
+       For example, the character class [aeiou] matches any lower case  vowel,
+       while  [^aeiou]  matches  any character that is not a lower case vowel.
        Note that a circumflex is just a convenient notation for specifying the
-       characters that are in the class by enumerating those that are  not.  A
-       class  that starts with a circumflex is not an assertion; it still con-
-       sumes a character from the subject string, and therefore  it  fails  if
+       characters  that  are in the class by enumerating those that are not. A
+       class that starts with a circumflex is not an assertion; it still  con-
+       sumes  a  character  from the subject string, and therefore it fails if
        the current pointer is at the end of the string.


-       Characters  in  a class may be specified by their code points using \o,
-       \x, or \N{U+hh..} in the usual way. When caseless matching is set,  any
-       letters  in a class represent both their upper case and lower case ver-
-       sions, so for example, a caseless [aeiou] matches "A" as well  as  "a",
-       and  a  caseless [^aeiou] does not match "A", whereas a caseful version
+       Characters in a class may be specified by their code points  using  \o,
+       \x,  or \N{U+hh..} in the usual way. When caseless matching is set, any
+       letters in a class represent both their upper case and lower case  ver-
+       sions,  so  for example, a caseless [aeiou] matches "A" as well as "a",
+       and a caseless [^aeiou] does not match "A", whereas a  caseful  version
        would.


-       Characters that might indicate line breaks are  never  treated  in  any
-       special  way  when  matching  character  classes,  whatever line-ending
-       sequence is in use,  and  whatever  setting  of  the  PCRE2_DOTALL  and
-       PCRE2_MULTILINE  options  is  used. A class such as [^a] always matches
+       Characters  that  might  indicate  line breaks are never treated in any
+       special way  when  matching  character  classes,  whatever  line-ending
+       sequence  is  in  use,  and  whatever  setting  of the PCRE2_DOTALL and
+       PCRE2_MULTILINE options is used. A class such as  [^a]  always  matches
        one of these characters.


        The generic character type escape sequences \d, \D, \h, \H, \p, \P, \s,
-       \S,  \v,  \V,  \w,  and \W may appear in a character class, and add the
-       characters that they  match  to  the  class.  For  example,  [\dABCDEF]
-       matches  any  hexadecimal  digit.  In  UTF  modes, the PCRE2_UCP option
-       affects the meanings of \d, \s, \w and their upper case partners,  just
-       as  it does when they appear outside a character class, as described in
-       the section  entitled  "Generic  character  types"  above.  The  escape
-       sequence  \b  has  a  different  meaning  inside  a character class; it
-       matches the backspace character. The sequences \B, \R, and \X  are  not
-       special  inside  a  character class. Like any other unrecognized escape
-       sequences, they cause an error. The same is true for \N when  not  fol-
+       \S, \v, \V, \w, and \W may appear in a character  class,  and  add  the
+       characters  that  they  match  to  the  class.  For example, [\dABCDEF]
+       matches any hexadecimal digit.  In  UTF  modes,  the  PCRE2_UCP  option
+       affects  the meanings of \d, \s, \w and their upper case partners, just
+       as it does when they appear outside a character class, as described  in
+       the  section  entitled  "Generic  character  types"  above.  The escape
+       sequence \b has a  different  meaning  inside  a  character  class;  it
+       matches  the  backspace character. The sequences \B, \R, and \X are not
+       special inside a character class. Like any  other  unrecognized  escape
+       sequences,  they  cause an error. The same is true for \N when not fol-
        lowed by an opening brace.


-       The  minus (hyphen) character can be used to specify a range of charac-
-       ters in a character  class.  For  example,  [d-m]  matches  any  letter
-       between  d  and  m,  inclusive.  If  a minus character is required in a
-       class, it must be escaped with a backslash  or  appear  in  a  position
-       where  it cannot be interpreted as indicating a range, typically as the
+       The minus (hyphen) character can be used to specify a range of  charac-
+       ters  in  a  character  class.  For  example,  [d-m] matches any letter
+       between d and m, inclusive. If a  minus  character  is  required  in  a
+       class,  it  must  be  escaped  with a backslash or appear in a position
+       where it cannot be interpreted as indicating a range, typically as  the
        first or last character in the class, or immediately after a range. For
-       example,  [b-d-z] matches letters in the range b to d, a hyphen charac-
+       example, [b-d-z] matches letters in the range b to d, a hyphen  charac-
        ter, or z.


        Perl treats a hyphen as a literal if it appears before or after a POSIX
        class (see below) or before or after a character type escape such as as
-       \d or \H.  However, unless the hyphen is  the  last  character  in  the
-       class,  Perl  outputs  a  warning  in its warning mode, as this is most
-       likely a user error. As PCRE2 has no facility for warning, an error  is
+       \d  or  \H.   However,  unless  the hyphen is the last character in the
+       class, Perl outputs a warning in its warning  mode,  as  this  is  most
+       likely  a user error. As PCRE2 has no facility for warning, an error is
        given in these cases.


        It is not possible to have the literal character "]" as the end charac-
-       ter of a range. A pattern such as [W-]46] is interpreted as a class  of
-       two  characters ("W" and "-") followed by a literal string "46]", so it
-       would match "W46]" or "-46]". However, if the "]"  is  escaped  with  a
-       backslash  it is interpreted as the end of range, so [W-\]46] is inter-
-       preted as a class containing a range followed by two other  characters.
-       The  octal or hexadecimal representation of "]" can also be used to end
+       ter  of a range. A pattern such as [W-]46] is interpreted as a class of
+       two characters ("W" and "-") followed by a literal string "46]", so  it
+       would  match  "W46]"  or  "-46]". However, if the "]" is escaped with a
+       backslash it is interpreted as the end of range, so [W-\]46] is  inter-
+       preted  as a class containing a range followed by two other characters.
+       The octal or hexadecimal representation of "]" can also be used to  end
        a range.


        Ranges normally include all code points between the start and end char-
-       acters,  inclusive.  They  can  also  be used for code points specified
+       acters, inclusive. They can also be  used  for  code  points  specified
        numerically, for example [\000-\037]. Ranges can include any characters
-       that  are  valid  for  the current mode. In any UTF mode, the so-called
-       "surrogate" characters (those whose code points lie between 0xd800  and
-       0xdfff  inclusive)  may  not  be  specified  explicitly by default (the
-       PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES option disables this  check).  How-
+       that are valid for the current mode. In any  UTF  mode,  the  so-called
+       "surrogate"  characters (those whose code points lie between 0xd800 and
+       0xdfff inclusive) may not  be  specified  explicitly  by  default  (the
+       PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES  option  disables this check). How-
        ever, ranges such as [\x{d7ff}-\x{e000}], which include the surrogates,
        are always permitted.


-       There is a special case in EBCDIC environments  for  ranges  whose  end
+       There  is  a  special  case in EBCDIC environments for ranges whose end
        points are both specified as literal letters in the same case. For com-
-       patibility with Perl, EBCDIC code points within the range that are  not
-       letters  are  omitted. For example, [h-k] matches only four characters,
+       patibility  with Perl, EBCDIC code points within the range that are not
+       letters are omitted. For example, [h-k] matches only  four  characters,
        even though the codes for h and k are 0x88 and 0x92, a range of 11 code
-       points.  However,  if  the range is specified numerically, for example,
+       points. However, if the range is specified  numerically,  for  example,
        [\x88-\x92] or [h-\x92], all code points are included.


        If a range that includes letters is used when caseless matching is set,
        it matches the letters in either case. For example, [W-c] is equivalent
-       to [][\\^_`wxyzabc], matched caselessly, and  in  a  non-UTF  mode,  if
-       character  tables  for  a French locale are in use, [\xc8-\xcb] matches
+       to  [][\\^_`wxyzabc],  matched  caselessly,  and  in a non-UTF mode, if
+       character tables for a French locale are in  use,  [\xc8-\xcb]  matches
        accented E characters in both cases.


-       A circumflex can conveniently be used with  the  upper  case  character
-       types  to specify a more restricted set of characters than the matching
-       lower case type.  For example, the class [^\W_] matches any  letter  or
+       A  circumflex  can  conveniently  be used with the upper case character
+       types to specify a more restricted set of characters than the  matching
+       lower  case  type.  For example, the class [^\W_] matches any letter or
        digit, but not underscore, whereas [\w] includes underscore. A positive
        character class should be read as "something OR something OR ..." and a
        negative class as "NOT something AND NOT something AND NOT ...".


-       The  only  metacharacters  that are recognized in character classes are
-       backslash, hyphen (only where it can be  interpreted  as  specifying  a
-       range),  circumflex  (only  at the start), opening square bracket (only
-       when it can be interpreted as introducing a POSIX class name, or for  a
-       special  compatibility  feature  -  see the next two sections), and the
+       The only metacharacters that are recognized in  character  classes  are
+       backslash,  hyphen  (only  where  it can be interpreted as specifying a
+       range), circumflex (only at the start), opening  square  bracket  (only
+       when  it can be interpreted as introducing a POSIX class name, or for a
+       special compatibility feature - see the next  two  sections),  and  the
        terminating  closing  square  bracket.  However,  escaping  other  non-
        alphanumeric characters does no harm.


@@ -7060,7 +7073,7 @@
POSIX CHARACTER CLASSES

        Perl supports the POSIX notation for character classes. This uses names
-       enclosed by [: and :] within the enclosing square brackets. PCRE2  also
+       enclosed  by [: and :] within the enclosing square brackets. PCRE2 also
        supports this notation. For example,


          [01[:alpha:]%]
@@ -7083,13 +7096,13 @@
          word     "word" characters (same as \w)
          xdigit   hexadecimal digits


-       The default "space" characters are HT (9), LF (10), VT (11),  FF  (12),
-       CR  (13),  and space (32). If locale-specific matching is taking place,
-       the list of space characters may be different; there may  be  fewer  or
+       The  default  "space" characters are HT (9), LF (10), VT (11), FF (12),
+       CR (13), and space (32). If locale-specific matching is  taking  place,
+       the  list  of  space characters may be different; there may be fewer or
        more of them. "Space" and \s match the same set of characters.


-       The  name  "word"  is  a Perl extension, and "blank" is a GNU extension
-       from Perl 5.8. Another Perl extension is negation, which  is  indicated
+       The name "word" is a Perl extension, and "blank"  is  a  GNU  extension
+       from  Perl  5.8. Another Perl extension is negation, which is indicated
        by a ^ character after the colon. For example,


          [12[:^digit:]]
@@ -7100,9 +7113,9 @@


        By default, characters with values greater than 127 do not match any of
        the POSIX character classes, although this may be different for charac-
-       ters  in  the range 128-255 when locale-specific matching is happening.
-       However, if the PCRE2_UCP option is passed to pcre2_compile(), some  of
-       the  classes are changed so that Unicode character properties are used.
+       ters in the range 128-255 when locale-specific matching  is  happening.
+       However,  if the PCRE2_UCP option is passed to pcre2_compile(), some of
+       the classes are changed so that Unicode character properties are  used.
        This  is  achieved  by  replacing  certain  POSIX  classes  with  other
        sequences, as follows:


@@ -7116,10 +7129,10 @@
          [:upper:]  becomes  \p{Lu}
          [:word:]   becomes  \p{Xwd}


-       Negated  versions, such as [:^alpha:] use \P instead of \p. Three other
+       Negated versions, such as [:^alpha:] use \P instead of \p. Three  other
        POSIX classes are handled specially in UCP mode:


-       [:graph:] This matches characters that have glyphs that mark  the  page
+       [:graph:] This  matches  characters that have glyphs that mark the page
                  when printed. In Unicode property terms, it matches all char-
                  acters with the L, M, N, P, S, or Cf properties, except for:


@@ -7128,22 +7141,22 @@
                    U+2066 - U+2069  Various "isolate"s



-       [:print:] This matches the same  characters  as  [:graph:]  plus  space
-                 characters  that  are  not controls, that is, characters with
+       [:print:] This  matches  the  same  characters  as [:graph:] plus space
+                 characters that are not controls, that  is,  characters  with
                  the Zs property.


        [:punct:] This matches all characters that have the Unicode P (punctua-
-                 tion)  property,  plus those characters with code points less
+                 tion) property, plus those characters with code  points  less
                  than 256 that have the S (Symbol) property.


-       The other POSIX classes are unchanged, and match only  characters  with
+       The  other  POSIX classes are unchanged, and match only characters with
        code points less than 256.



COMPATIBILITY FEATURE FOR WORD BOUNDARIES

-       In  the POSIX.2 compliant library that was included in 4.4BSD Unix, the
-       ugly syntax [[:<:]] and [[:>:]] is used for matching  "start  of  word"
+       In the POSIX.2 compliant library that was included in 4.4BSD Unix,  the
+       ugly  syntax  [[:<:]]  and [[:>:]] is used for matching "start of word"
        and "end of word". PCRE2 treats these items as follows:


          [[:<:]]  is converted to  \b(?=\w)
@@ -7150,37 +7163,37 @@
          [[:>:]]  is converted to  \b(?<=\w)


        Only these exact character sequences are recognized. A sequence such as
-       [a[:<:]b] provokes error for an unrecognized  POSIX  class  name.  This
-       support  is not compatible with Perl. It is provided to help migrations
+       [a[:<:]b]  provokes  error  for  an unrecognized POSIX class name. This
+       support is not compatible with Perl. It is provided to help  migrations
        from other environments, and is best not used in any new patterns. Note
-       that  \b matches at the start and the end of a word (see "Simple asser-
-       tions" above), and in a Perl-style pattern the preceding  or  following
-       character  normally  shows  which  is  wanted, without the need for the
-       assertions that are used above in order to give exactly the  POSIX  be-
+       that \b matches at the start and the end of a word (see "Simple  asser-
+       tions"  above),  and in a Perl-style pattern the preceding or following
+       character normally shows which is wanted,  without  the  need  for  the
+       assertions  that  are used above in order to give exactly the POSIX be-
        haviour.



VERTICAL BAR

-       Vertical  bar characters are used to separate alternative patterns. For
+       Vertical bar characters are used to separate alternative patterns.  For
        example, the pattern


          gilbert|sullivan


-       matches either "gilbert" or "sullivan". Any number of alternatives  may
-       appear,  and  an  empty  alternative  is  permitted (matching the empty
+       matches  either "gilbert" or "sullivan". Any number of alternatives may
+       appear, and an empty  alternative  is  permitted  (matching  the  empty
        string). The matching process tries each alternative in turn, from left
-       to  right, and the first one that succeeds is used. If the alternatives
-       are within a subpattern (defined below), "succeeds" means matching  the
+       to right, and the first one that succeeds is used. If the  alternatives
+       are  within a subpattern (defined below), "succeeds" means matching the
        rest of the main pattern as well as the alternative in the subpattern.



INTERNAL OPTION SETTING

-       The  settings  of  the  PCRE2_CASELESS,  PCRE2_MULTILINE, PCRE2_DOTALL,
-       PCRE2_EXTENDED, PCRE2_EXTENDED_MORE, and PCRE2_NO_AUTO_CAPTURE  options
+       The settings  of  the  PCRE2_CASELESS,  PCRE2_MULTILINE,  PCRE2_DOTALL,
+       PCRE2_EXTENDED,  PCRE2_EXTENDED_MORE, and PCRE2_NO_AUTO_CAPTURE options
        (which are Perl-compatible) can be changed from within the pattern by a
-       sequence of Perl option letters enclosed  between  "(?"  and  ")".  The
+       sequence  of  Perl  option  letters  enclosed between "(?" and ")". The
        option letters are


          i  for PCRE2_CASELESS
@@ -7191,30 +7204,36 @@
          xx for PCRE2_EXTENDED_MORE


        For example, (?im) sets caseless, multiline matching. It is also possi-
-       ble to unset these options by preceding the letter with a  hyphen.  The
-       two  "extended"  options are not independent; unsetting either one can-
-       cels the effects of both of them.
+       ble  to  unset  these  options by preceding the relevant letters with a
+       hyphen, for example (?-im). The two "extended" options are not indepen-
+       dent; unsetting either one cancels the effects of both of them.


-       A  combined  setting  and  unsetting  such  as  (?im-sx),  which   sets
-       PCRE2_CASELESS  and  PCRE2_MULTILINE  while  unsetting PCRE2_DOTALL and
-       PCRE2_EXTENDED, is also permitted. If a letter appears both before  and
-       after  the  hyphen, the option is unset. An empty options setting "(?)"
-       is allowed. Needless to say, it has no effect.
+       A   combined  setting  and  unsetting  such  as  (?im-sx),  which  sets
+       PCRE2_CASELESS and PCRE2_MULTILINE  while  unsetting  PCRE2_DOTALL  and
+       PCRE2_EXTENDED,  is  also  permitted. Only one hyphen may appear in the
+       options string. If a letter appears both before and after  the  hyphen,
+       the  option  is unset. An empty options setting "(?)" is allowed. Need-
+       less to say, it has no effect.


-       The PCRE2-specific options PCRE2_DUPNAMES  and  PCRE2_UNGREEDY  can  be
-       changed  in  the  same  way as the Perl-compatible options by using the
-       characters J and U respectively.
+       If the first character following (? is a circumflex, it causes  all  of
+       the  above  options to be unset. Thus, (?^) is equivalent to (?-imnsx).
+       Letters may follow the circumflex to  cause  some  options  to  be  re-
+       instated, but a hyphen may not appear.


-       When one of these option changes occurs at  top  level  (that  is,  not
-       inside  subpattern parentheses), the change applies to the remainder of
-       the pattern that follows. An option change  within  a  subpattern  (see
-       below  for  a description of subpatterns) affects only that part of the
+       The  PCRE2-specific  options  PCRE2_DUPNAMES  and PCRE2_UNGREEDY can be
+       changed in the same way as the Perl-compatible  options  by  using  the
+       characters J and U respectively. However, these are not unset by (?^).
+
+       When  one  of  these  option  changes occurs at top level (that is, not
+       inside subpattern parentheses), the change applies to the remainder  of
+       the  pattern  that  follows.  An option change within a subpattern (see
+       below for a description of subpatterns) affects only that part  of  the
        subpattern that follows it, so


          (a(?i)b)c


-       matches abc and aBc and no other strings  (assuming  PCRE2_CASELESS  is
-       not  used).   By this means, options can be made to have different set-
+       matches  abc  and  aBc and no other strings (assuming PCRE2_CASELESS is
+       not used).  By this means, options can be made to have  different  set-
        tings in different parts of the pattern. Any changes made in one alter-
        native do carry on into subsequent branches within the same subpattern.
        For example,
@@ -7221,13 +7240,13 @@


          (a(?i)b|c)


-       matches "ab", "aB", "c", and "C", even though  when  matching  "C"  the
-       first  branch  is  abandoned before the option setting. This is because
-       the effects of option settings happen at compile time. There  would  be
+       matches  "ab",  "aB",  "c",  and "C", even though when matching "C" the
+       first branch is abandoned before the option setting.  This  is  because
+       the  effects  of option settings happen at compile time. There would be
        some very weird behaviour otherwise.


-       As  a  convenient shorthand, if any option settings are required at the
-       start of a non-capturing subpattern (see the next section), the  option
+       As a convenient shorthand, if any option settings are required  at  the
+       start  of a non-capturing subpattern (see the next section), the option
        letters may appear between the "?" and the ":". Thus the two patterns


          (?i:saturday|sunday)
@@ -7235,14 +7254,14 @@


        match exactly the same set of strings.


-       Note:  There  are  other  PCRE2-specific options that can be set by the
+       Note: There are other PCRE2-specific options that can  be  set  by  the
        application when the compiling function is called. The pattern can con-
-       tain  special  leading  sequences  such as (*CRLF) to override what the
-       application has set or what has been defaulted. Details  are  given  in
-       the  section  entitled  "Newline  sequences"  above. There are also the
-       (*UTF) and (*UCP) leading sequences that can be used  to  set  UTF  and
-       Unicode  property  modes;  they are equivalent to setting the PCRE2_UTF
-       and PCRE2_UCP options, respectively. However, the application  can  set
+       tain special leading sequences such as (*CRLF)  to  override  what  the
+       application  has  set  or what has been defaulted. Details are given in
+       the section entitled "Newline sequences"  above.  There  are  also  the
+       (*UTF)  and  (*UCP)  leading  sequences that can be used to set UTF and
+       Unicode property modes; they are equivalent to  setting  the  PCRE2_UTF
+       and  PCRE2_UCP  options, respectively. However, the application can set
        the PCRE2_NEVER_UTF and PCRE2_NEVER_UCP options, which lock out the use
        of the (*UTF) and (*UCP) sequences.


@@ -7256,18 +7275,18 @@

          cat(aract|erpillar|)


-       matches  "cataract",  "caterpillar", or "cat". Without the parentheses,
+       matches "cataract", "caterpillar", or "cat". Without  the  parentheses,
        it would match "cataract", "erpillar" or an empty string.


-       2. It sets up the subpattern as  a  capturing  subpattern.  This  means
+       2.  It  sets  up  the  subpattern as a capturing subpattern. This means
        that, when the whole pattern matches, the portion of the subject string
-       that matched the subpattern is passed back to  the  caller,  separately
-       from  the portion that matched the whole pattern. (This applies only to
-       the traditional matching function; the DFA matching function  does  not
+       that  matched  the  subpattern is passed back to the caller, separately
+       from the portion that matched the whole pattern. (This applies only  to
+       the  traditional  matching function; the DFA matching function does not
        support capturing.)


        Opening parentheses are counted from left to right (starting from 1) to
-       obtain numbers for the  capturing  subpatterns.  For  example,  if  the
+       obtain  numbers  for  the  capturing  subpatterns.  For example, if the
        string "the red king" is matched against the pattern


          the ((red|white) (king|queen))
@@ -7275,12 +7294,12 @@
        the captured substrings are "red king", "red", and "king", and are num-
        bered 1, 2, and 3, respectively.


-       The fact that plain parentheses fulfil  two  functions  is  not  always
-       helpful.   There are often times when a grouping subpattern is required
-       without a capturing requirement. If an opening parenthesis is  followed
-       by  a question mark and a colon, the subpattern does not do any captur-
-       ing, and is not counted when computing the  number  of  any  subsequent
-       capturing  subpatterns. For example, if the string "the white queen" is
+       The  fact  that  plain  parentheses  fulfil two functions is not always
+       helpful.  There are often times when a grouping subpattern is  required
+       without  a capturing requirement. If an opening parenthesis is followed
+       by a question mark and a colon, the subpattern does not do any  captur-
+       ing,  and  is  not  counted when computing the number of any subsequent
+       capturing subpatterns. For example, if the string "the white queen"  is
        matched against the pattern


          the ((?:red|white) (king|queen))
@@ -7288,8 +7307,8 @@
        the captured substrings are "white queen" and "queen", and are numbered
        1 and 2. The maximum number of capturing subpatterns is 65535.


-       As  a  convenient shorthand, if any option settings are required at the
-       start of a non-capturing subpattern,  the  option  letters  may  appear
+       As a convenient shorthand, if any option settings are required  at  the
+       start  of  a  non-capturing  subpattern,  the option letters may appear
        between the "?" and the ":". Thus the two patterns


          (?i:saturday|sunday)
@@ -7296,9 +7315,9 @@
          (?:(?i)saturday|sunday)


        match exactly the same set of strings. Because alternative branches are
-       tried from left to right, and options are not reset until  the  end  of
-       the  subpattern is reached, an option setting in one branch does affect
-       subsequent branches, so the above patterns match "SUNDAY"  as  well  as
+       tried  from  left  to right, and options are not reset until the end of
+       the subpattern is reached, an option setting in one branch does  affect
+       subsequent  branches,  so  the above patterns match "SUNDAY" as well as
        "Saturday".



@@ -7305,20 +7324,20 @@
DUPLICATE SUBPATTERN NUMBERS

        Perl 5.10 introduced a feature whereby each alternative in a subpattern
-       uses the same numbers for its capturing parentheses. Such a  subpattern
-       starts  with (?| and is itself a non-capturing subpattern. For example,
+       uses  the same numbers for its capturing parentheses. Such a subpattern
+       starts with (?| and is itself a non-capturing subpattern. For  example,
        consider this pattern:


          (?|(Sat)ur|(Sun))day


-       Because the two alternatives are inside a (?| group, both sets of  cap-
-       turing  parentheses  are  numbered one. Thus, when the pattern matches,
-       you can look at captured substring number  one,  whichever  alternative
-       matched.  This  construct  is useful when you want to capture part, but
+       Because  the two alternatives are inside a (?| group, both sets of cap-
+       turing parentheses are numbered one. Thus, when  the  pattern  matches,
+       you  can  look  at captured substring number one, whichever alternative
+       matched. This construct is useful when you want to  capture  part,  but
        not all, of one of a number of alternatives. Inside a (?| group, paren-
-       theses  are  numbered as usual, but the number is reset at the start of
-       each branch. The numbers of any capturing parentheses that  follow  the
-       subpattern  start after the highest number used in any branch. The fol-
+       theses are numbered as usual, but the number is reset at the  start  of
+       each  branch.  The numbers of any capturing parentheses that follow the
+       subpattern start after the highest number used in any branch. The  fol-
        lowing example is taken from the Perl documentation. The numbers under-
        neath show in which buffer the captured content will be stored.


@@ -7326,14 +7345,14 @@
          / ( a )  (?| x ( y ) z | (p (q) r) | (t) u (v) ) ( z ) /x
          # 1            2         2  3        2     3     4


-       A  backreference  to  a  numbered subpattern uses the most recent value
-       that is set for that number by any subpattern.  The  following  pattern
+       A backreference to a numbered subpattern uses  the  most  recent  value
+       that  is  set  for that number by any subpattern. The following pattern
        matches "abcabc" or "defdef":


          /(?|(abc)|(def))\1/


-       In  contrast,  a subroutine call to a numbered subpattern always refers
-       to the first one in the pattern with the given  number.  The  following
+       In contrast, a subroutine call to a numbered subpattern  always  refers
+       to  the  first  one in the pattern with the given number. The following
        pattern matches "abcabc" or "defabc":


          /(?|(abc)|(def))(?1)/
@@ -7341,47 +7360,47 @@
        A relative reference such as (?-1) is no different: it is just a conve-
        nient way of computing an absolute group number.


-       If a condition test for a subpattern's having matched refers to a  non-
-       unique  number, the test is true if any of the subpatterns of that num-
+       If  a condition test for a subpattern's having matched refers to a non-
+       unique number, the test is true if any of the subpatterns of that  num-
        ber have matched.


-       An alternative approach to using this "branch reset" feature is to  use
+       An  alternative approach to using this "branch reset" feature is to use
        duplicate named subpatterns, as described in the next section.



NAMED SUBPATTERNS

-       Identifying  capturing  parentheses  by number is simple, but it can be
-       very hard to keep track of the numbers in complicated  regular  expres-
-       sions.  Furthermore,  if  an  expression  is  modified, the numbers may
+       Identifying capturing parentheses by number is simple, but  it  can  be
+       very  hard  to keep track of the numbers in complicated regular expres-
+       sions. Furthermore, if an  expression  is  modified,  the  numbers  may
        change. To help with this difficulty, PCRE2 supports the naming of sub-
        patterns. This feature was not added to Perl until release 5.10. Python
-       had the feature earlier, and PCRE1 introduced it at release 4.0,  using
-       the  Python syntax. PCRE2 supports both the Perl and the Python syntax.
-       Perl allows identically numbered subpatterns to have  different  names,
+       had  the feature earlier, and PCRE1 introduced it at release 4.0, using
+       the Python syntax. PCRE2 supports both the Perl and the Python  syntax.
+       Perl  allows  identically numbered subpatterns to have different names,
        but PCRE2 does not.


-       In  PCRE2, a subpattern can be named in one of three ways: (?<name>...)
-       or (?'name'...) as in Perl, or (?P<name>...) as in  Python.  References
+       In PCRE2, a subpattern can be named in one of three ways:  (?<name>...)
+       or  (?'name'...)  as in Perl, or (?P<name>...) as in Python. References
        to capturing parentheses from other parts of the pattern, such as back-
-       references, recursion, and conditions, can be made by name as  well  as
+       references,  recursion,  and conditions, can be made by name as well as
        by number.


-       Names  consist of up to 32 alphanumeric characters and underscores, but
-       must start with a non-digit.  Named  capturing  parentheses  are  still
-       allocated  numbers  as  well as names, exactly as if the names were not
+       Names consist of up to 32 alphanumeric characters and underscores,  but
+       must  start  with  a  non-digit.  Named capturing parentheses are still
+       allocated numbers as well as names, exactly as if the  names  were  not
        present. The PCRE2 API provides function calls for extracting the name-
-       to-number  translation  table  from  a compiled pattern. There are also
+       to-number translation table from a compiled  pattern.  There  are  also
        convenience functions for extracting a captured substring by name.


-       By default, a name must be unique within a pattern, but it is  possible
-       to  relax  this constraint by setting the PCRE2_DUPNAMES option at com-
-       pile time.  (Duplicate names are also always permitted for  subpatterns
-       with  the  same  number,  set up as described in the previous section.)
-       Duplicate names can be useful for patterns where only one  instance  of
+       By  default, a name must be unique within a pattern, but it is possible
+       to relax this constraint by setting the PCRE2_DUPNAMES option  at  com-
+       pile  time.  (Duplicate names are also always permitted for subpatterns
+       with the same number, set up as described  in  the  previous  section.)
+       Duplicate  names  can be useful for patterns where only one instance of
        the named parentheses can match.  Suppose you want to match the name of
-       a weekday, either as a 3-letter abbreviation or as the full  name,  and
-       in  both  cases  you  want  to  extract  the abbreviation. This pattern
+       a  weekday,  either as a 3-letter abbreviation or as the full name, and
+       in both cases you  want  to  extract  the  abbreviation.  This  pattern
        (ignoring the line breaks) does the job:


          (?<DN>Mon|Fri|Sun)(?:day)?|
@@ -7390,18 +7409,18 @@
          (?<DN>Thu)(?:rsday)?|
          (?<DN>Sat)(?:urday)?


-       There are five capturing substrings, but only one is ever set  after  a
+       There  are  five capturing substrings, but only one is ever set after a
        match.  (An alternative way of solving this problem is to use a "branch
        reset" subpattern, as described in the previous section.)


-       The convenience functions for extracting the data by name  returns  the
-       substring  for  the first (and in this example, the only) subpattern of
-       that name that matched. This saves searching  to  find  which  numbered
+       The  convenience  functions for extracting the data by name returns the
+       substring for the first (and in this example, the only)  subpattern  of
+       that  name  that  matched.  This saves searching to find which numbered
        subpattern it was.


        If you make a backreference to a non-unique named subpattern from else-
-       where in the pattern, the subpatterns to  which  the  name  refers  are
-       checked  in  the order in which they appear in the overall pattern. The
+       where  in  the  pattern,  the  subpatterns to which the name refers are
+       checked in the order in which they appear in the overall  pattern.  The
        first one that is set is used for the reference. For example, this pat-
        tern matches both "foofoo" and "barbar" but not "foobar" or "barfoo":


@@ -7409,22 +7428,22 @@


        If you make a subroutine call to a non-unique named subpattern, the one
-       that corresponds to the first occurrence of the name is  used.  In  the
+       that  corresponds  to  the first occurrence of the name is used. In the
        absence of duplicate numbers (see the previous section) this is the one
        with the lowest number.


        If you use a named reference in a condition test (see the section about
        conditions below), either to check whether a subpattern has matched, or
-       to check for recursion, all subpatterns with the same name are  tested.
-       If  the condition is true for any one of them, the overall condition is
-       true. This is the same behaviour as  testing  by  number.  For  further
-       details  of  the  interfaces  for  handling  named subpatterns, see the
+       to  check for recursion, all subpatterns with the same name are tested.
+       If the condition is true for any one of them, the overall condition  is
+       true.  This  is  the  same  behaviour as testing by number. For further
+       details of the interfaces  for  handling  named  subpatterns,  see  the
        pcre2api documentation.


        Warning: You cannot use different names to distinguish between two sub-
-       patterns  with the same number because PCRE2 uses only the numbers when
+       patterns with the same number because PCRE2 uses only the numbers  when
        matching. For this reason, an error is given at compile time if differ-
-       ent  names  are given to subpatterns with the same number. However, you
+       ent names are given to subpatterns with the same number.  However,  you
        can always give the same name to subpatterns with the same number, even
        when PCRE2_DUPNAMES is not set.


@@ -7431,7 +7450,7 @@

REPETITION

-       Repetition  is  specified  by  quantifiers, which can follow any of the
+       Repetition is specified by quantifiers, which can  follow  any  of  the
        following items:


          a literal data character
@@ -7445,17 +7464,17 @@
          a parenthesized subpattern (including most assertions)
          a subroutine call to a subpattern (recursive or otherwise)


-       The general repetition quantifier specifies a minimum and maximum  num-
-       ber  of  permitted matches, by giving the two numbers in curly brackets
-       (braces), separated by a comma. The numbers must be  less  than  65536,
+       The  general repetition quantifier specifies a minimum and maximum num-
+       ber of permitted matches, by giving the two numbers in  curly  brackets
+       (braces),  separated  by  a comma. The numbers must be less than 65536,
        and the first must be less than or equal to the second. For example:


          z{2,4}


-       matches  "zz",  "zzz",  or  "zzzz". A closing brace on its own is not a
-       special character. If the second number is omitted, but  the  comma  is
-       present,  there  is  no upper limit; if the second number and the comma
-       are both omitted, the quantifier specifies an exact number of  required
+       matches "zz", "zzz", or "zzzz". A closing brace on its  own  is  not  a
+       special  character.  If  the second number is omitted, but the comma is
+       present, there is no upper limit; if the second number  and  the  comma
+       are  both omitted, the quantifier specifies an exact number of required
        matches. Thus


          [aeiou]{3,}
@@ -7464,26 +7483,26 @@


          \d{8}


-       matches  exactly  8  digits. An opening curly bracket that appears in a
-       position where a quantifier is not allowed, or one that does not  match
-       the  syntax of a quantifier, is taken as a literal character. For exam-
+       matches exactly 8 digits. An opening curly bracket that  appears  in  a
+       position  where a quantifier is not allowed, or one that does not match
+       the syntax of a quantifier, is taken as a literal character. For  exam-
        ple, {,6} is not a quantifier, but a literal string of four characters.


        In UTF modes, quantifiers apply to characters rather than to individual
-       code  units. Thus, for example, \x{100}{2} matches two characters, each
+       code units. Thus, for example, \x{100}{2} matches two characters,  each
        of which is represented by a two-byte sequence in a UTF-8 string. Simi-
-       larly,  \X{3} matches three Unicode extended grapheme clusters, each of
-       which may be several code units long (and  they  may  be  of  different
+       larly, \X{3} matches three Unicode extended grapheme clusters, each  of
+       which  may  be  several  code  units long (and they may be of different
        lengths).


        The quantifier {0} is permitted, causing the expression to behave as if
        the previous item and the quantifier were not present. This may be use-
-       ful  for  subpatterns that are referenced as subroutines from elsewhere
+       ful for subpatterns that are referenced as subroutines  from  elsewhere
        in the pattern (but see also the section entitled "Defining subpatterns
-       for  use  by  reference only" below). Items other than subpatterns that
+       for use by reference only" below). Items other  than  subpatterns  that
        have a {0} quantifier are omitted from the compiled pattern.


-       For convenience, the three most common quantifiers have  single-charac-
+       For  convenience, the three most common quantifiers have single-charac-
        ter abbreviations:


          *    is equivalent to {0,}
@@ -7490,24 +7509,24 @@
          +    is equivalent to {1,}
          ?    is equivalent to {0,1}


-       It  is  possible  to construct infinite loops by following a subpattern
+       It is possible to construct infinite loops by  following  a  subpattern
        that can match no characters with a quantifier that has no upper limit,
        for example:


          (a?)*


-       Earlier  versions  of  Perl  and PCRE1 used to give an error at compile
+       Earlier versions of Perl and PCRE1 used to give  an  error  at  compile
        time for such patterns. However, because there are cases where this can
        be useful, such patterns are now accepted, but if any repetition of the
-       subpattern does in fact match no characters, the loop is forcibly  bro-
+       subpattern  does in fact match no characters, the loop is forcibly bro-
        ken.


-       By  default,  the quantifiers are "greedy", that is, they match as much
-       as possible (up to the maximum  number  of  permitted  times),  without
-       causing  the  rest of the pattern to fail. The classic example of where
+       By default, the quantifiers are "greedy", that is, they match  as  much
+       as  possible  (up  to  the  maximum number of permitted times), without
+       causing the rest of the pattern to fail. The classic example  of  where
        this gives problems is in trying to match comments in C programs. These
-       appear  between  /*  and  */ and within the comment, individual * and /
-       characters may appear. An attempt to match C comments by  applying  the
+       appear between /* and */ and within the comment,  individual  *  and  /
+       characters  may  appear. An attempt to match C comments by applying the
        pattern


          /\*.*\*/
@@ -7516,19 +7535,19 @@


          /* first comment */  not comment  /* second comment */


-       fails,  because it matches the entire string owing to the greediness of
+       fails, because it matches the entire string owing to the greediness  of
        the .*  item.


        If a quantifier is followed by a question mark, it ceases to be greedy,
-       and  instead  matches the minimum number of times possible, so the pat-
+       and instead matches the minimum number of times possible, so  the  pat-
        tern


          /\*.*?\*/


-       does the right thing with the C comments. The meaning  of  the  various
-       quantifiers  is  not  otherwise  changed,  just the preferred number of
-       matches.  Do not confuse this use of question mark with its  use  as  a
-       quantifier  in its own right. Because it has two uses, it can sometimes
+       does  the  right  thing with the C comments. The meaning of the various
+       quantifiers is not otherwise changed,  just  the  preferred  number  of
+       matches.   Do  not  confuse this use of question mark with its use as a
+       quantifier in its own right. Because it has two uses, it can  sometimes
        appear doubled, as in


          \d??\d
@@ -7537,45 +7556,45 @@
        only way the rest of the pattern matches.


        If the PCRE2_UNGREEDY option is set (an option that is not available in
-       Perl), the quantifiers are not greedy by default, but  individual  ones
-       can  be  made  greedy  by following them with a question mark. In other
+       Perl),  the  quantifiers are not greedy by default, but individual ones
+       can be made greedy by following them with a  question  mark.  In  other
        words, it inverts the default behaviour.


-       When a parenthesized subpattern is quantified  with  a  minimum  repeat
-       count  that is greater than 1 or with a limited maximum, more memory is
-       required for the compiled pattern, in proportion to  the  size  of  the
+       When  a  parenthesized  subpattern  is quantified with a minimum repeat
+       count that is greater than 1 or with a limited maximum, more memory  is
+       required  for  the  compiled  pattern, in proportion to the size of the
        minimum or maximum.


-       If  a  pattern  starts  with  .*  or  .{0,} and the PCRE2_DOTALL option
-       (equivalent to Perl's /s) is set, thus allowing the dot to  match  new-
-       lines,  the  pattern  is  implicitly anchored, because whatever follows
-       will be tried against every character position in the  subject  string,
-       so  there  is  no  point  in retrying the overall match at any position
+       If a pattern starts with  .*  or  .{0,}  and  the  PCRE2_DOTALL  option
+       (equivalent  to  Perl's /s) is set, thus allowing the dot to match new-
+       lines, the pattern is implicitly  anchored,  because  whatever  follows
+       will  be  tried against every character position in the subject string,
+       so there is no point in retrying the  overall  match  at  any  position
        after the first. PCRE2 normally treats such a pattern as though it were
        preceded by \A.


-       In  cases  where  it  is known that the subject string contains no new-
-       lines, it is worth setting PCRE2_DOTALL in order to obtain  this  opti-
+       In cases where it is known that the subject  string  contains  no  new-
+       lines,  it  is worth setting PCRE2_DOTALL in order to obtain this opti-
        mization, or alternatively, using ^ to indicate anchoring explicitly.


-       However,  there  are  some cases where the optimization cannot be used.
-       When .*  is inside capturing parentheses that  are  the  subject  of  a
-       backreference  elsewhere  in the pattern, a match at the start may fail
+       However, there are some cases where the optimization  cannot  be  used.
+       When  .*   is  inside  capturing  parentheses that are the subject of a
+       backreference elsewhere in the pattern, a match at the start  may  fail
        where a later one succeeds. Consider, for example:


          (.*)abc\1


-       If the subject is "xyz123abc123" the match point is the fourth  charac-
+       If  the subject is "xyz123abc123" the match point is the fourth charac-
        ter. For this reason, such a pattern is not implicitly anchored.


-       Another  case where implicit anchoring is not applied is when the lead-
-       ing .* is inside an atomic group. Once again, a match at the start  may
+       Another case where implicit anchoring is not applied is when the  lead-
+       ing  .* is inside an atomic group. Once again, a match at the start may
        fail where a later one succeeds. Consider this pattern:


          (?>.*?a)b


-       It  matches "ab" in the subject "aab". The use of the backtracking con-
-       trol verbs (*PRUNE) and (*SKIP) also  disable  this  optimization,  and
+       It matches "ab" in the subject "aab". The use of the backtracking  con-
+       trol  verbs  (*PRUNE)  and  (*SKIP) also disable this optimization, and
        there is an option, PCRE2_NO_DOTSTAR_ANCHOR, to do so explicitly.


        When a capturing subpattern is repeated, the value captured is the sub-
@@ -7584,8 +7603,8 @@
          (tweedle[dume]{3}\s*)+


        has matched "tweedledum tweedledee" the value of the captured substring
-       is  "tweedledee".  However,  if there are nested capturing subpatterns,
-       the corresponding captured values may have been set in previous  itera-
+       is "tweedledee". However, if there are  nested  capturing  subpatterns,
+       the  corresponding captured values may have been set in previous itera-
        tions. For example, after


          (a|(b))+
@@ -7595,53 +7614,53 @@


ATOMIC GROUPING AND POSSESSIVE QUANTIFIERS

-       With  both  maximizing ("greedy") and minimizing ("ungreedy" or "lazy")
-       repetition, failure of what follows normally causes the  repeated  item
-       to  be  re-evaluated to see if a different number of repeats allows the
-       rest of the pattern to match. Sometimes it is useful to  prevent  this,
-       either  to  change the nature of the match, or to cause it fail earlier
-       than it otherwise might, when the author of the pattern knows there  is
+       With both maximizing ("greedy") and minimizing ("ungreedy"  or  "lazy")
+       repetition,  failure  of what follows normally causes the repeated item
+       to be re-evaluated to see if a different number of repeats  allows  the
+       rest  of  the pattern to match. Sometimes it is useful to prevent this,
+       either to change the nature of the match, or to cause it  fail  earlier
+       than  it otherwise might, when the author of the pattern knows there is
        no point in carrying on.


-       Consider,  for  example, the pattern \d+foo when applied to the subject
+       Consider, for example, the pattern \d+foo when applied to  the  subject
        line


          123456bar


        After matching all 6 digits and then failing to match "foo", the normal
-       action  of  the matcher is to try again with only 5 digits matching the
-       \d+ item, and then with  4,  and  so  on,  before  ultimately  failing.
-       "Atomic  grouping"  (a  term taken from Jeffrey Friedl's book) provides
-       the means for specifying that once a subpattern has matched, it is  not
+       action of the matcher is to try again with only 5 digits  matching  the
+       \d+  item,  and  then  with  4,  and  so on, before ultimately failing.
+       "Atomic grouping" (a term taken from Jeffrey  Friedl's  book)  provides
+       the  means for specifying that once a subpattern has matched, it is not
        to be re-evaluated in this way.


-       If  we  use atomic grouping for the previous example, the matcher gives
-       up immediately on failing to match "foo" the first time.  The  notation
+       If we use atomic grouping for the previous example, the  matcher  gives
+       up  immediately  on failing to match "foo" the first time. The notation
        is a kind of special parenthesis, starting with (?> as in this example:


          (?>\d+)foo


-       This  kind  of  parenthesis "locks up" the  part of the pattern it con-
-       tains once it has matched, and a failure further into  the  pattern  is
-       prevented  from  backtracking into it. Backtracking past it to previous
+       This kind of parenthesis "locks up" the  part of the  pattern  it  con-
+       tains  once  it  has matched, and a failure further into the pattern is
+       prevented from backtracking into it. Backtracking past it  to  previous
        items, however, works as normal.


-       An alternative description is that a subpattern of  this  type  matches
-       exactly  the  string of characters that an identical standalone pattern
+       An  alternative  description  is that a subpattern of this type matches
+       exactly the string of characters that an identical  standalone  pattern
        would match, if anchored at the current point in the subject string.


        Atomic grouping subpatterns are not capturing subpatterns. Simple cases
        such as the above example can be thought of as a maximizing repeat that
-       must swallow everything it can. So, while both \d+ and  \d+?  are  pre-
-       pared  to  adjust  the number of digits they match in order to make the
+       must  swallow  everything  it can. So, while both \d+ and \d+? are pre-
+       pared to adjust the number of digits they match in order  to  make  the
        rest of the pattern match, (?>\d+) can only match an entire sequence of
        digits.


-       Atomic  groups in general can of course contain arbitrarily complicated
-       subpatterns, and can be nested. However, when  the  subpattern  for  an
+       Atomic groups in general can of course contain arbitrarily  complicated
+       subpatterns,  and  can  be  nested. However, when the subpattern for an
        atomic group is just a single repeated item, as in the example above, a
-       simpler notation, called a "possessive quantifier" can  be  used.  This
-       consists  of  an  additional  + character following a quantifier. Using
+       simpler  notation,  called  a "possessive quantifier" can be used. This
+       consists of an additional + character  following  a  quantifier.  Using
        this notation, the previous example can be rewritten as


          \d++foo
@@ -7651,46 +7670,46 @@


          (abc|xyz){2,3}+


-       Possessive   quantifiers   are   always  greedy;  the  setting  of  the
-       PCRE2_UNGREEDY option is ignored. They are a  convenient  notation  for
-       the  simpler  forms of atomic group. However, there is no difference in
+       Possessive  quantifiers  are  always  greedy;  the   setting   of   the
+       PCRE2_UNGREEDY  option  is  ignored. They are a convenient notation for
+       the simpler forms of atomic group. However, there is no  difference  in
        the meaning of a possessive quantifier and the equivalent atomic group,
-       though  there  may  be a performance difference; possessive quantifiers
+       though there may be a performance  difference;  possessive  quantifiers
        should be slightly faster.


-       The possessive quantifier syntax is an extension to the Perl  5.8  syn-
-       tax.   Jeffrey  Friedl  originated the idea (and the name) in the first
+       The  possessive  quantifier syntax is an extension to the Perl 5.8 syn-
+       tax.  Jeffrey Friedl originated the idea (and the name)  in  the  first
        edition of his book. Mike McCloskey liked it, so implemented it when he
        built Sun's Java package, and PCRE1 copied it from there. It ultimately
        found its way into Perl at release 5.10.


-       PCRE2 has an optimization  that  automatically  "possessifies"  certain
-       simple  pattern constructs. For example, the sequence A+B is treated as
-       A++B because there is no point in backtracking into a sequence  of  A's
+       PCRE2  has  an  optimization  that automatically "possessifies" certain
+       simple pattern constructs. For example, the sequence A+B is treated  as
+       A++B  because  there is no point in backtracking into a sequence of A's
        when B must follow.  This feature can be disabled by the PCRE2_NO_AUTO-
        POSSESS option, or starting the pattern with (*NO_AUTO_POSSESS).


-       When a pattern contains an unlimited repeat inside  a  subpattern  that
-       can  itself  be  repeated  an  unlimited number of times, the use of an
-       atomic group is the only way to avoid some  failing  matches  taking  a
+       When  a  pattern  contains an unlimited repeat inside a subpattern that
+       can itself be repeated an unlimited number of  times,  the  use  of  an
+       atomic  group  is  the  only way to avoid some failing matches taking a
        very long time indeed. The pattern


          (\D+|<\d+>)*[!?]


-       matches  an  unlimited number of substrings that either consist of non-
-       digits, or digits enclosed in <>, followed by either ! or  ?.  When  it
+       matches an unlimited number of substrings that either consist  of  non-
+       digits,  or  digits  enclosed in <>, followed by either ! or ?. When it
        matches, it runs quickly. However, if it is applied to


          aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa


-       it  takes  a  long  time  before reporting failure. This is because the
-       string can be divided between the internal \D+ repeat and the  external
-       *  repeat  in  a  large  number of ways, and all have to be tried. (The
-       example uses [!?] rather than a single character at  the  end,  because
-       both  PCRE2  and Perl have an optimization that allows for fast failure
-       when a single character is used. They remember the last single  charac-
-       ter  that  is required for a match, and fail early if it is not present
-       in the string.) If the pattern is changed so that  it  uses  an  atomic
+       it takes a long time before reporting  failure.  This  is  because  the
+       string  can be divided between the internal \D+ repeat and the external
+       * repeat in a large number of ways, and all  have  to  be  tried.  (The
+       example  uses  [!?]  rather than a single character at the end, because
+       both PCRE2 and Perl have an optimization that allows for  fast  failure
+       when  a single character is used. They remember the last single charac-
+       ter that is required for a match, and fail early if it is  not  present
+       in  the  string.)  If  the pattern is changed so that it uses an atomic
        group, like this:


          ((?>\D+)|<\d+>)*[!?]
@@ -7701,29 +7720,29 @@
 BACKREFERENCES


        Outside a character class, a backslash followed by a digit greater than
-       0 (and possibly further digits) is a backreference to a capturing  sub-
-       pattern  earlier  (that is, to its left) in the pattern, provided there
+       0  (and possibly further digits) is a backreference to a capturing sub-
+       pattern earlier (that is, to its left) in the pattern,  provided  there
        have been that many previous capturing left parentheses.


-       However, if the decimal number following the backslash is less than  8,
-       it  is  always  taken  as  a backreference, and causes an error only if
-       there are not that many capturing left parentheses in the  entire  pat-
-       tern.  In  other words, the parentheses that are referenced need not be
-       to the left of the reference for numbers less than 8. A "forward  back-
-       reference"  of  this  type can make sense when a repetition is involved
-       and the subpattern to the right has participated in an  earlier  itera-
+       However,  if the decimal number following the backslash is less than 8,
+       it is always taken as a backreference, and  causes  an  error  only  if
+       there  are  not that many capturing left parentheses in the entire pat-
+       tern. In other words, the parentheses that are referenced need  not  be
+       to  the left of the reference for numbers less than 8. A "forward back-
+       reference" of this type can make sense when a  repetition  is  involved
+       and  the  subpattern to the right has participated in an earlier itera-
        tion.


-       It  is  not  possible  to have a numerical "forward backreference" to a
-       subpattern whose number is 8  or  more  using  this  syntax  because  a
-       sequence  such  as  \50 is interpreted as a character defined in octal.
+       It is not possible to have a numerical  "forward  backreference"  to  a
+       subpattern  whose  number  is  8  or  more  using this syntax because a
+       sequence such as \50 is interpreted as a character  defined  in  octal.
        See the subsection entitled "Non-printing characters" above for further
-       details  of  the  handling of digits following a backslash. There is no
-       such problem when named parentheses are used. A  backreference  to  any
+       details of the handling of digits following a backslash.  There  is  no
+       such  problem  when  named parentheses are used. A backreference to any
        subpattern is possible using named parentheses (see below).


-       Another  way  of  avoiding  the ambiguity inherent in the use of digits
-       following a backslash is to use the \g  escape  sequence.  This  escape
+       Another way of avoiding the ambiguity inherent in  the  use  of  digits
+       following  a  backslash  is  to use the \g escape sequence. This escape
        must be followed by a signed or unsigned number, optionally enclosed in
        braces. These examples are all identical:


@@ -7731,9 +7750,9 @@
          (ring), \g1
          (ring), \g{1}


-       An unsigned number specifies an absolute reference without the  ambigu-
+       An  unsigned number specifies an absolute reference without the ambigu-
        ity that is present in the older syntax. It is also useful when literal
-       digits follow the reference. A signed number is a  relative  reference.
+       digits  follow  the reference. A signed number is a relative reference.
        Consider this example:


          (abc(def)ghi)\g{-1}
@@ -7740,37 +7759,37 @@


        The sequence \g{-1} is a reference to the most recently started captur-
        ing subpattern before \g, that is, is it equivalent to \2 in this exam-
-       ple.   Similarly, \g{-2} would be equivalent to \1. The use of relative
-       references can be helpful in long patterns, and also in  patterns  that
-       are  created  by  joining  together  fragments  that contain references
+       ple.  Similarly, \g{-2} would be equivalent to \1. The use of  relative
+       references  can  be helpful in long patterns, and also in patterns that
+       are created by  joining  together  fragments  that  contain  references
        within themselves.


-       The sequence \g{+1} is a reference to the  next  capturing  subpattern.
-       This  kind  of forward reference can be useful it patterns that repeat.
+       The  sequence  \g{+1}  is a reference to the next capturing subpattern.
+       This kind of forward reference can be useful it patterns  that  repeat.
        Perl does not support the use of + in this way.


        A backreference matches whatever actually matched the capturing subpat-
-       tern  in  the current subject string, rather than anything matching the
-       subpattern itself (see "Subpatterns as subroutines" below for a way  of
+       tern in the current subject string, rather than anything  matching  the
+       subpattern  itself (see "Subpatterns as subroutines" below for a way of
        doing that). So the pattern


          (sens|respons)e and \1ibility


-       matches  "sense and sensibility" and "response and responsibility", but
-       not "sense and responsibility". If caseful matching is in force at  the
-       time  of  the backreference, the case of letters is relevant. For exam-
+       matches "sense and sensibility" and "response and responsibility",  but
+       not  "sense and responsibility". If caseful matching is in force at the
+       time of the backreference, the case of letters is relevant.  For  exam-
        ple,


          ((?i)rah)\s+\1


-       matches "rah rah" and "RAH RAH", but not "RAH  rah",  even  though  the
+       matches  "rah  rah"  and  "RAH RAH", but not "RAH rah", even though the
        original capturing subpattern is matched caselessly.


-       There  are  several  different  ways of writing backreferences to named
-       subpatterns. The .NET syntax \k{name} and the Perl syntax  \k<name>  or
-       \k'name'  are supported, as is the Python syntax (?P=name). Perl 5.10's
-       unified backreference syntax, in which \g can be used for both  numeric
-       and  named  references,  is  also supported. We could rewrite the above
+       There are several different ways of  writing  backreferences  to  named
+       subpatterns.  The  .NET syntax \k{name} and the Perl syntax \k<name> or
+       \k'name' are supported, as is the Python syntax (?P=name). Perl  5.10's
+       unified  backreference syntax, in which \g can be used for both numeric
+       and named references, is also supported. We  could  rewrite  the  above
        example in any of the following ways:


          (?<p1>(?i)rah)\s+\k<p1>
@@ -7778,31 +7797,31 @@
          (?P<p1>(?i)rah)\s+(?P=p1)
          (?<p1>(?i)rah)\s+\g{p1}


-       A subpattern that is referenced by  name  may  appear  in  the  pattern
+       A  subpattern  that  is  referenced  by  name may appear in the pattern
        before or after the reference.


-       There  may  be more than one backreference to the same subpattern. If a
-       subpattern has not actually been used in a particular match, any  back-
+       There may be more than one backreference to the same subpattern.  If  a
+       subpattern  has not actually been used in a particular match, any back-
        references to it always fail by default. For example, the pattern


          (a|(bc))\2


-       always  fails  if  it starts to match "a" rather than "bc". However, if
+       always fails if it starts to match "a" rather than  "bc".  However,  if
        the PCRE2_MATCH_UNSET_BACKREF option is set at compile time, a backref-
        erence to an unset value matches an empty string.


-       Because  there may be many capturing parentheses in a pattern, all dig-
-       its following a backslash are taken as part of a  potential  backrefer-
-       ence  number.   If  the  pattern continues with a digit character, some
-       delimiter  must  be  used  to  terminate  the  backreference.  If   the
-       PCRE2_EXTENDED  option  is set, this can be white space. Otherwise, the
+       Because there may be many capturing parentheses in a pattern, all  dig-
+       its  following  a backslash are taken as part of a potential backrefer-
+       ence number.  If the pattern continues with  a  digit  character,  some
+       delimiter   must  be  used  to  terminate  the  backreference.  If  the
+       PCRE2_EXTENDED option is set, this can be white space.  Otherwise,  the
        \g{ syntax or an empty comment (see "Comments" below) can be used.


    Recursive backreferences


-       A backreference that occurs inside the parentheses to which  it  refers
-       fails  when  the subpattern is first used, so, for example, (a\1) never
-       matches.  However, such references can be useful inside  repeated  sub-
+       A  backreference  that occurs inside the parentheses to which it refers
+       fails when the subpattern is first used, so, for example,  (a\1)  never
+       matches.   However,  such references can be useful inside repeated sub-
        patterns. For example, the pattern


          (a|b\1)+
@@ -7810,74 +7829,74 @@
        matches any number of "a"s and also "aba", "ababbaa" etc. At each iter-
        ation of the subpattern, the backreference matches the character string
        corresponding to the previous iteration. In order for this to work, the
-       pattern must be such that the first iteration does not  need  to  match
-       the  backreference. This can be done using alternation, as in the exam-
+       pattern  must  be  such that the first iteration does not need to match
+       the backreference. This can be done using alternation, as in the  exam-
        ple above, or by a quantifier with a minimum of zero.


-       Backreferences of this type cause the group that they reference  to  be
-       treated  as  an atomic group.  Once the whole group has been matched, a
-       subsequent matching failure cannot cause backtracking into  the  middle
+       Backreferences  of  this type cause the group that they reference to be
+       treated as an atomic group.  Once the whole group has been  matched,  a
+       subsequent  matching  failure cannot cause backtracking into the middle
        of the group.



ASSERTIONS

-       An  assertion  is  a  test on the characters following or preceding the
+       An assertion is a test on the characters  following  or  preceding  the
        current matching point that does not consume any characters. The simple
-       assertions  coded  as  \b,  \B,  \A,  \G, \Z, \z, ^ and $ are described
+       assertions coded as \b, \B, \A, \G, \Z,  \z,  ^  and  $  are  described
        above.


-       More complicated assertions are coded as  subpatterns.  There  are  two
-       kinds:  those  that  look  ahead of the current position in the subject
-       string, and those that look behind it, and in each  case  an  assertion
-       may  be  positive  (must  succeed for matching to continue) or negative
+       More  complicated  assertions  are  coded as subpatterns. There are two
+       kinds: those that look ahead of the current  position  in  the  subject
+       string,  and  those  that look behind it, and in each case an assertion
+       may be positive (must succeed for matching  to  continue)  or  negative
        (must not succeed for matching to continue). An assertion subpattern is
        matched in the normal way, except that, when matching continues after a
        successful assertion, the matching position in the subject string is as
        it was before the assertion was processed.


-       Assertion  subpatterns  are  not capturing subpatterns. If an assertion
-       contains capturing subpatterns within it, these  are  counted  for  the
-       purposes  of  numbering the capturing subpatterns in the whole pattern.
-       Within each branch of an assertion, locally captured substrings may  be
+       Assertion subpatterns are not capturing subpatterns.  If  an  assertion
+       contains  capturing  subpatterns  within  it, these are counted for the
+       purposes of numbering the capturing subpatterns in the  whole  pattern.
+       Within  each branch of an assertion, locally captured substrings may be
        referenced in the usual way.  For example, a sequence such as (.)\g{-1}
        can be used to check that two adjacent characters are the same.


-       When a branch within an assertion fails to match, any  substrings  that
-       were  captured  are  discarded (as happens with any pattern branch that
-       fails to match). A  negative  assertion  succeeds  only  when  all  its
+       When  a  branch within an assertion fails to match, any substrings that
+       were captured are discarded (as happens with any  pattern  branch  that
+       fails  to  match).  A  negative  assertion  succeeds  only when all its
        branches fail to match; this means that no captured substrings are ever
-       retained after a successful negative assertion. When an assertion  con-
+       retained  after a successful negative assertion. When an assertion con-
        tains a matching branch, what happens depends on the type of assertion.


-       For  a  positive  assertion, internally captured substrings in the suc-
-       cessful branch are retained, and matching continues with the next  pat-
-       tern  item  after  the  assertion. For a negative assertion, a matching
-       branch means that the assertion has failed. If the assertion  is  being
-       used  as  a condition in a conditional subpattern (see below), captured
-       substrings are retained,  because  matching  continues  with  the  "no"
+       For a positive assertion, internally captured substrings  in  the  suc-
+       cessful  branch are retained, and matching continues with the next pat-
+       tern item after the assertion. For a  negative  assertion,  a  matching
+       branch  means  that the assertion has failed. If the assertion is being
+       used as a condition in a conditional subpattern (see  below),  captured
+       substrings  are  retained,  because  matching  continues  with the "no"
        branch of the condition. For other failing negative assertions, control
        passes to the previous backtracking point, thus discarding any captured
        strings within the assertion.


-       For   compatibility  with  Perl,  most  assertion  subpatterns  may  be
-       repeated; though it makes no sense to assert  the  same  thing  several
-       times,  the  side  effect  of capturing parentheses may occasionally be
-       useful. However, an assertion that forms the  condition  for  a  condi-
-       tional  subpattern may not be quantified. In practice, for other asser-
+       For  compatibility  with  Perl,  most  assertion  subpatterns  may   be
+       repeated;  though  it  makes  no sense to assert the same thing several
+       times, the side effect of capturing  parentheses  may  occasionally  be
+       useful.  However,  an  assertion  that forms the condition for a condi-
+       tional subpattern may not be quantified. In practice, for other  asser-
        tions, there only three cases:


-       (1) If the quantifier is {0}, the  assertion  is  never  obeyed  during
-       matching.   However,  it  may  contain internal capturing parenthesized
+       (1)  If  the  quantifier  is  {0}, the assertion is never obeyed during
+       matching.  However, it may  contain  internal  capturing  parenthesized
        groups that are called from elsewhere via the subroutine mechanism.


-       (2) If quantifier is {0,n} where n is greater than zero, it is  treated
-       as  if  it  were  {0,1}.  At run time, the rest of the pattern match is
+       (2)  If quantifier is {0,n} where n is greater than zero, it is treated
+       as if it were {0,1}. At run time, the rest  of  the  pattern  match  is
        tried with and without the assertion, the order depending on the greed-
        iness of the quantifier.


-       (3)  If  the minimum repetition is greater than zero, the quantifier is
-       ignored.  The assertion is obeyed just  once  when  encountered  during
+       (3) If the minimum repetition is greater than zero, the  quantifier  is
+       ignored.   The  assertion  is  obeyed just once when encountered during
        matching.


    Lookahead assertions
@@ -7887,38 +7906,38 @@


          \w+(?=;)


-       matches a word followed by a semicolon, but does not include the  semi-
+       matches  a word followed by a semicolon, but does not include the semi-
        colon in the match, and


          foo(?!bar)


-       matches  any  occurrence  of  "foo" that is not followed by "bar". Note
+       matches any occurrence of "foo" that is not  followed  by  "bar".  Note
        that the apparently similar pattern


          (?!foo)bar


-       does not find an occurrence of "bar"  that  is  preceded  by  something
-       other  than "foo"; it finds any occurrence of "bar" whatsoever, because
+       does  not  find  an  occurrence  of "bar" that is preceded by something
+       other than "foo"; it finds any occurrence of "bar" whatsoever,  because
        the assertion (?!foo) is always true when the next three characters are
        "bar". A lookbehind assertion is needed to achieve the other effect.


        If you want to force a matching failure at some point in a pattern, the
-       most convenient way to do it is  with  (?!)  because  an  empty  string
-       always  matches, so an assertion that requires there not to be an empty
+       most  convenient  way  to  do  it  is with (?!) because an empty string
+       always matches, so an assertion that requires there not to be an  empty
        string must always fail.  The backtracking control verb (*FAIL) or (*F)
        is a synonym for (?!).


    Lookbehind assertions


-       Lookbehind  assertions start with (?<= for positive assertions and (?<!
+       Lookbehind assertions start with (?<= for positive assertions and  (?<!
        for negative assertions. For example,


          (?<!foo)bar


-       does find an occurrence of "bar" that is not  preceded  by  "foo".  The
-       contents  of  a  lookbehind  assertion are restricted such that all the
+       does  find  an  occurrence  of "bar" that is not preceded by "foo". The
+       contents of a lookbehind assertion are restricted  such  that  all  the
        strings it matches must have a fixed length. However, if there are sev-
-       eral  top-level  alternatives,  they  do  not all have to have the same
+       eral top-level alternatives, they do not all  have  to  have  the  same
        fixed length. Thus


          (?<=bullock|donkey)
@@ -7927,66 +7946,66 @@


          (?<!dogs?|cats?)


-       causes an error at compile time. Branches that match  different  length
-       strings  are permitted only at the top level of a lookbehind assertion.
+       causes  an  error at compile time. Branches that match different length
+       strings are permitted only at the top level of a lookbehind  assertion.
        This is an extension compared with Perl, which requires all branches to
        match the same length of string. An assertion such as


          (?<=ab(c|de))


-       is  not  permitted,  because  its single top-level branch can match two
-       different lengths, but it is acceptable to PCRE2 if  rewritten  to  use
+       is not permitted, because its single top-level  branch  can  match  two
+       different  lengths,  but  it is acceptable to PCRE2 if rewritten to use
        two top-level branches:


          (?<=abc|abde)


-       In  some  cases, the escape sequence \K (see above) can be used instead
+       In some cases, the escape sequence \K (see above) can be  used  instead
        of a lookbehind assertion to get round the fixed-length restriction.


-       The implementation of lookbehind assertions is, for  each  alternative,
-       to  temporarily  move the current position back by the fixed length and
+       The  implementation  of lookbehind assertions is, for each alternative,
+       to temporarily move the current position back by the fixed  length  and
        then try to match. If there are insufficient characters before the cur-
        rent position, the assertion fails.


-       In  UTF-8  and  UTF-16 modes, PCRE2 does not allow the \C escape (which
-       matches a single code unit even in a UTF mode) to appear in  lookbehind
-       assertions,  because  it makes it impossible to calculate the length of
-       the lookbehind. The \X and \R escapes, which can match  different  num-
+       In UTF-8 and UTF-16 modes, PCRE2 does not allow the  \C  escape  (which
+       matches  a single code unit even in a UTF mode) to appear in lookbehind
+       assertions, because it makes it impossible to calculate the  length  of
+       the  lookbehind.  The \X and \R escapes, which can match different num-
        bers of code units, are never permitted in lookbehinds.


-       "Subroutine"  calls  (see below) such as (?2) or (?&X) are permitted in
-       lookbehinds, as long as the subpattern matches a  fixed-length  string.
-       However,  recursion,  that is, a "subroutine" call into a group that is
+       "Subroutine" calls (see below) such as (?2) or (?&X) are  permitted  in
+       lookbehinds,  as  long as the subpattern matches a fixed-length string.
+       However, recursion, that is, a "subroutine" call into a group  that  is
        already active, is not supported.


        Perl does not support backreferences in lookbehinds. PCRE2 does support
-       them,    but    only    if    certain    conditions    are   met.   The
-       PCRE2_MATCH_UNSET_BACKREF option must not be set, there must be no  use
+       them,   but   only    if    certain    conditions    are    met.    The
+       PCRE2_MATCH_UNSET_BACKREF  option must not be set, there must be no use
        of (?| in the pattern (it creates duplicate subpattern numbers), and if
-       the backreference is by name, the name must be unique. Of  course,  the
-       referenced  subpattern  must  itself  be of fixed length. The following
+       the  backreference  is by name, the name must be unique. Of course, the
+       referenced subpattern must itself be of  fixed  length.  The  following
        pattern matches words containing at least two characters that begin and
        end with the same character:


           \b(\w)\w++(?<=\1)


-       Possessive  quantifiers  can  be  used  in  conjunction with lookbehind
+       Possessive quantifiers can  be  used  in  conjunction  with  lookbehind
        assertions to specify efficient matching of fixed-length strings at the
        end of subject strings. Consider a simple pattern such as


          abcd$


-       when  applied  to  a  long string that does not match. Because matching
-       proceeds from left to right, PCRE2 will look for each "a" in  the  sub-
-       ject  and  then see if what follows matches the rest of the pattern. If
+       when applied to a long string that does  not  match.  Because  matching
+       proceeds  from  left to right, PCRE2 will look for each "a" in the sub-
+       ject and then see if what follows matches the rest of the  pattern.  If
        the pattern is specified as


          ^.*abcd$


-       the initial .* matches the entire string at first, but when this  fails
+       the  initial .* matches the entire string at first, but when this fails
        (because there is no following "a"), it backtracks to match all but the
-       last character, then all but the last two characters, and so  on.  Once
-       again  the search for "a" covers the entire string, from right to left,
+       last  character,  then all but the last two characters, and so on. Once
+       again the search for "a" covers the entire string, from right to  left,
        so we are no better off. However, if the pattern is written as


          ^.*+(?<=abcd)
@@ -7993,8 +8012,8 @@


        there can be no backtracking for the .*+ item because of the possessive
        quantifier; it can match only the entire string. The subsequent lookbe-
-       hind assertion does a single test on the last four  characters.  If  it
-       fails,  the  match  fails  immediately. For long strings, this approach
+       hind  assertion  does  a single test on the last four characters. If it
+       fails, the match fails immediately. For  long  strings,  this  approach
        makes a significant difference to the processing time.


    Using multiple assertions
@@ -8003,18 +8022,18 @@


          (?<=\d{3})(?<!999)foo


-       matches "foo" preceded by three digits that are not "999". Notice  that
-       each  of  the  assertions is applied independently at the same point in
-       the subject string. First there is a  check  that  the  previous  three
-       characters  are  all  digits,  and  then there is a check that the same
+       matches  "foo" preceded by three digits that are not "999". Notice that
+       each of the assertions is applied independently at the  same  point  in
+       the  subject  string.  First  there  is a check that the previous three
+       characters are all digits, and then there is  a  check  that  the  same
        three characters are not "999".  This pattern does not match "foo" pre-
-       ceded  by  six  characters,  the first of which are digits and the last
-       three of which are not "999". For example, it  doesn't  match  "123abc-
+       ceded by six characters, the first of which are  digits  and  the  last
+       three  of  which  are not "999". For example, it doesn't match "123abc-
        foo". A pattern to do that is


          (?<=\d{3}...)(?<!999)foo


-       This  time  the  first assertion looks at the preceding six characters,
+       This time the first assertion looks at the  preceding  six  characters,
        checking that the first three are digits, and then the second assertion
        checks that the preceding three characters are not "999".


@@ -8022,29 +8041,29 @@

          (?<=(?<!foo)bar)baz


-       matches  an occurrence of "baz" that is preceded by "bar" which in turn
+       matches an occurrence of "baz" that is preceded by "bar" which in  turn
        is not preceded by "foo", while


          (?<=\d{3}(?!999)...)foo


-       is another pattern that matches "foo" preceded by three digits and  any
+       is  another pattern that matches "foo" preceded by three digits and any
        three characters that are not "999".



CONDITIONAL SUBPATTERNS

-       It  is possible to cause the matching process to obey a subpattern con-
-       ditionally or to choose between two alternative subpatterns,  depending
-       on  the result of an assertion, or whether a specific capturing subpat-
-       tern has already been matched. The two possible  forms  of  conditional
+       It is possible to cause the matching process to obey a subpattern  con-
+       ditionally  or to choose between two alternative subpatterns, depending
+       on the result of an assertion, or whether a specific capturing  subpat-
+       tern  has  already  been matched. The two possible forms of conditional
        subpattern are:


          (?(condition)yes-pattern)
          (?(condition)yes-pattern|no-pattern)


-       If  the  condition is satisfied, the yes-pattern is used; otherwise the
-       no-pattern (if present) is used. An absent no-pattern is equivalent  to
-       an  empty string (it always matches). If there are more than two alter-
+       If the condition is satisfied, the yes-pattern is used;  otherwise  the
+       no-pattern  (if present) is used. An absent no-pattern is equivalent to
+       an empty string (it always matches). If there are more than two  alter-
        natives in the subpattern, a compile-time error occurs. Each of the two
        alternatives may itself contain nested subpatterns of any form, includ-
        ing  conditional  subpatterns;  the  restriction  to  two  alternatives
@@ -8054,57 +8073,57 @@
          (?(1) (A|B|C) | (D | (?(2)E|F) | E) )



-       There are five kinds of condition: references  to  subpatterns,  refer-
-       ences  to  recursion,  two pseudo-conditions called DEFINE and VERSION,
+       There  are  five  kinds of condition: references to subpatterns, refer-
+       ences to recursion, two pseudo-conditions called  DEFINE  and  VERSION,
        and assertions.


    Checking for a used subpattern by number


-       If the text between the parentheses consists of a sequence  of  digits,
+       If  the  text between the parentheses consists of a sequence of digits,
        the condition is true if a capturing subpattern of that number has pre-
-       viously matched. If there is more than one  capturing  subpattern  with
-       the  same  number  (see  the earlier section about duplicate subpattern
-       numbers), the condition is true if any of them have matched. An  alter-
-       native  notation is to precede the digits with a plus or minus sign. In
-       this case, the subpattern number is relative rather than absolute.  The
-       most  recently opened parentheses can be referenced by (?(-1), the next
-       most recent by (?(-2), and so on. Inside loops it can also  make  sense
+       viously  matched.  If  there is more than one capturing subpattern with
+       the same number (see the earlier  section  about  duplicate  subpattern
+       numbers),  the condition is true if any of them have matched. An alter-
+       native notation is to precede the digits with a plus or minus sign.  In
+       this  case, the subpattern number is relative rather than absolute. The
+       most recently opened parentheses can be referenced by (?(-1), the  next
+       most  recent  by (?(-2), and so on. Inside loops it can also make sense
        to refer to subsequent groups. The next parentheses to be opened can be
-       referenced as (?(+1), and so on. (The value zero in any of these  forms
+       referenced  as (?(+1), and so on. (The value zero in any of these forms
        is not used; it provokes a compile-time error.)


-       Consider  the  following  pattern, which contains non-significant white
-       space to make it more readable (assume the PCRE2_EXTENDED  option)  and
+       Consider the following pattern, which  contains  non-significant  white
+       space  to  make it more readable (assume the PCRE2_EXTENDED option) and
        to divide it into three parts for ease of discussion:


          ( \( )?    [^()]+    (?(1) \) )


-       The  first  part  matches  an optional opening parenthesis, and if that
+       The first part matches an optional opening  parenthesis,  and  if  that
        character is present, sets it as the first captured substring. The sec-
-       ond  part  matches one or more characters that are not parentheses. The
-       third part is a conditional subpattern that tests whether  or  not  the
-       first  set  of  parentheses  matched.  If they did, that is, if subject
-       started with an opening parenthesis, the condition is true, and so  the
-       yes-pattern  is  executed and a closing parenthesis is required. Other-
-       wise, since no-pattern is not present, the subpattern matches  nothing.
-       In  other  words,  this  pattern matches a sequence of non-parentheses,
+       ond part matches one or more characters that are not  parentheses.  The
+       third  part  is  a conditional subpattern that tests whether or not the
+       first set of parentheses matched. If they  did,  that  is,  if  subject
+       started  with an opening parenthesis, the condition is true, and so the
+       yes-pattern is executed and a closing parenthesis is  required.  Other-
+       wise,  since no-pattern is not present, the subpattern matches nothing.
+       In other words, this pattern matches  a  sequence  of  non-parentheses,
        optionally enclosed in parentheses.


-       If you were embedding this pattern in a larger one,  you  could  use  a
+       If  you  were  embedding  this pattern in a larger one, you could use a
        relative reference:


          ...other stuff... ( \( )?    [^()]+    (?(-1) \) ) ...


-       This  makes  the  fragment independent of the parentheses in the larger
+       This makes the fragment independent of the parentheses  in  the  larger
        pattern.


    Checking for a used subpattern by name


-       Perl uses the syntax (?(<name>)...) or (?('name')...)  to  test  for  a
-       used  subpattern  by  name.  For compatibility with earlier versions of
-       PCRE1, which had this facility before Perl, the syntax (?(name)...)  is
-       also  recognized.  Note,  however, that undelimited names consisting of
-       the letter R followed by digits are ambiguous (see the  following  sec-
+       Perl  uses  the  syntax  (?(<name>)...) or (?('name')...) to test for a
+       used subpattern by name. For compatibility  with  earlier  versions  of
+       PCRE1,  which had this facility before Perl, the syntax (?(name)...) is
+       also recognized. Note, however, that undelimited  names  consisting  of
+       the  letter  R followed by digits are ambiguous (see the following sec-
        tion).


        Rewriting the above example to use a named subpattern gives this:
@@ -8111,31 +8130,31 @@


          (?<OPEN> \( )?    [^()]+    (?(<OPEN>) \) )


-       If  the  name used in a condition of this kind is a duplicate, the test
-       is applied to all subpatterns of the same name, and is true if any  one
+       If the name used in a condition of this kind is a duplicate,  the  test
+       is  applied to all subpatterns of the same name, and is true if any one
        of them has matched.


    Checking for pattern recursion


-       "Recursion"  in  this sense refers to any subroutine-like call from one
-       part of the pattern to another, whether or not it  is  actually  recur-
-       sive.  See  the sections entitled "Recursive patterns" and "Subpatterns
+       "Recursion" in this sense refers to any subroutine-like call  from  one
+       part  of  the  pattern to another, whether or not it is actually recur-
+       sive. See the sections entitled "Recursive patterns"  and  "Subpatterns
        as subroutines" below for details of recursion and subpattern calls.


-       If a condition is the string (R), and there is no subpattern  with  the
-       name  R,  the condition is true if matching is currently in a recursion
-       or subroutine call to the whole pattern or any  subpattern.  If  digits
-       follow  the  letter  R,  and there is no subpattern with that name, the
+       If  a  condition is the string (R), and there is no subpattern with the
+       name R, the condition is true if matching is currently in  a  recursion
+       or  subroutine  call  to the whole pattern or any subpattern. If digits
+       follow the letter R, and there is no subpattern  with  that  name,  the
        condition is true if the most recent call is into a subpattern with the
-       given  number,  which must exist somewhere in the overall pattern. This
+       given number, which must exist somewhere in the overall  pattern.  This
        is a contrived example that is equivalent to a+b:


          ((?(R1)a+|(?1)b))


-       However, in both cases, if there is a subpattern with a matching  name,
-       the  condition  tests  for  its  being set, as described in the section
-       above, instead of testing for recursion. For example, creating a  group
-       with  the  name  R1  by  adding (?<R1>) to the above pattern completely
+       However,  in both cases, if there is a subpattern with a matching name,
+       the condition tests for its being set,  as  described  in  the  section
+       above,  instead of testing for recursion. For example, creating a group
+       with the name R1 by adding (?<R1>)  to  the  above  pattern  completely
        changes its meaning.


        If a name preceded by ampersand follows the letter R, for example:
@@ -8146,7 +8165,7 @@
        of that name (which must exist within the pattern).


        This condition does not check the entire recursion stack. It tests only
-       the current level. If the name used in a condition of this  kind  is  a
+       the  current  level.  If the name used in a condition of this kind is a
        duplicate, the test is applied to all subpatterns of the same name, and
        is true if any one of them is the most recent recursion.


@@ -8155,10 +8174,10 @@
    Defining subpatterns for use by reference only


        If the condition is the string (DEFINE), the condition is always false,
-       even  if there is a group with the name DEFINE. In this case, there may
+       even if there is a group with the name DEFINE. In this case, there  may
        be only one alternative in the subpattern. It is always skipped if con-
-       trol  reaches  this point in the pattern; the idea of DEFINE is that it
-       can be used to define subroutines that can  be  referenced  from  else-
+       trol reaches this point in the pattern; the idea of DEFINE is  that  it
+       can  be  used  to  define subroutines that can be referenced from else-
        where. (The use of subroutines is described below.) For example, a pat-
        tern to match an IPv4 address such as "192.168.23.245" could be written
        like this (ignore white space and line breaks):
@@ -8166,53 +8185,53 @@
          (?(DEFINE) (?<byte> 2[0-4]\d | 25[0-5] | 1\d\d | [1-9]?\d) )
          \b (?&byte) (\.(?&byte)){3} \b


-       The  first part of the pattern is a DEFINE group inside which a another
-       group named "byte" is defined. This matches an individual component  of
-       an  IPv4  address  (a number less than 256). When matching takes place,
-       this part of the pattern is skipped because DEFINE acts  like  a  false
-       condition.  The  rest of the pattern uses references to the named group
-       to match the four dot-separated components of an IPv4 address,  insist-
+       The first part of the pattern is a DEFINE group inside which a  another
+       group  named "byte" is defined. This matches an individual component of
+       an IPv4 address (a number less than 256). When  matching  takes  place,
+       this  part  of  the pattern is skipped because DEFINE acts like a false
+       condition. The rest of the pattern uses references to the  named  group
+       to  match the four dot-separated components of an IPv4 address, insist-
        ing on a word boundary at each end.


    Checking the PCRE2 version


-       Programs  that link with a PCRE2 library can check the version by call-
-       ing pcre2_config() with appropriate arguments.  Users  of  applications
-       that  do  not have access to the underlying code cannot do this. A spe-
-       cial "condition" called VERSION exists to allow such users to  discover
+       Programs that link with a PCRE2 library can check the version by  call-
+       ing  pcre2_config()  with  appropriate arguments. Users of applications
+       that do not have access to the underlying code cannot do this.  A  spe-
+       cial  "condition" called VERSION exists to allow such users to discover
        which version of PCRE2 they are dealing with by using this condition to
-       match a string such as "yesno". VERSION must be followed either by  "="
+       match  a string such as "yesno". VERSION must be followed either by "="
        or ">=" and a version number.  For example:


          (?(VERSION>=10.4)yes|no)


-       This  pattern matches "yes" if the PCRE2 version is greater or equal to
-       10.4, or "no" otherwise. The fractional part of the version number  may
+       This pattern matches "yes" if the PCRE2 version is greater or equal  to
+       10.4,  or "no" otherwise. The fractional part of the version number may
        not contain more than two digits.


    Assertion conditions


-       If  the  condition  is  not  in any of the above formats, it must be an
-       assertion.  This may be a positive or negative lookahead or  lookbehind
-       assertion.  Consider  this  pattern,  again  containing non-significant
+       If the condition is not in any of the above  formats,  it  must  be  an
+       assertion.   This may be a positive or negative lookahead or lookbehind
+       assertion. Consider  this  pattern,  again  containing  non-significant
        white space, and with the two alternatives on the second line:


          (?(?=[^a-z]*[a-z])
          \d{2}-[a-z]{3}-\d{2}  |  \d{2}-\d{2}-\d{2} )


-       The condition  is  a  positive  lookahead  assertion  that  matches  an
-       optional  sequence of non-letters followed by a letter. In other words,
-       it tests for the presence of at least one letter in the subject.  If  a
-       letter  is found, the subject is matched against the first alternative;
-       otherwise it is  matched  against  the  second.  This  pattern  matches
-       strings  in  one  of the two forms dd-aaa-dd or dd-dd-dd, where aaa are
+       The  condition  is  a  positive  lookahead  assertion  that  matches an
+       optional sequence of non-letters followed by a letter. In other  words,
+       it  tests  for the presence of at least one letter in the subject. If a
+       letter is found, the subject is matched against the first  alternative;
+       otherwise  it  is  matched  against  the  second.  This pattern matches
+       strings in one of the two forms dd-aaa-dd or dd-dd-dd,  where  aaa  are
        letters and dd are digits.


-       When an assertion that is a condition contains  capturing  subpatterns,
-       any  capturing that occurs in a matching branch is retained afterwards,
+       When  an  assertion that is a condition contains capturing subpatterns,
+       any capturing that occurs in a matching branch is retained  afterwards,
        for both positive and negative assertions, because matching always con-
        tinues after the assertion, whether it succeeds or fails. (Compare non-
-       conditional assertions, when captures are retained  only  for  positive
+       conditional  assertions,  when  captures are retained only for positive
        assertions that succeed.)



@@ -8219,44 +8238,44 @@
COMMENTS

        There are two ways of including comments in patterns that are processed
-       by PCRE2. In both cases, the start of the comment  must  not  be  in  a
-       character  class,  nor  in  the middle of any other sequence of related
-       characters such as (?: or a subpattern name or number.  The  characters
+       by  PCRE2.  In  both  cases,  the start of the comment must not be in a
+       character class, nor in the middle of any  other  sequence  of  related
+       characters  such  as (?: or a subpattern name or number. The characters
        that make up a comment play no part in the pattern matching.


-       The  sequence (?# marks the start of a comment that continues up to the
-       next closing parenthesis. Nested parentheses are not permitted. If  the
-       PCRE2_EXTENDED  option is set, an unescaped # character also introduces
-       a comment, which in this case continues to immediately after  the  next
-       newline  character  or character sequence in the pattern. Which charac-
-       ters are interpreted as newlines is controlled by an option  passed  to
-       the  compiling  function  or  by a special sequence at the start of the
-       pattern, as described in the  section  entitled  "Newline  conventions"
-       above.  Note  that the end of this type of comment is a literal newline
-       sequence in the pattern; escape sequences that happen  to  represent  a
-       newline   do  not  count.  For  example,  consider  this  pattern  when
-       PCRE2_EXTENDED is set, and the default  newline  convention  (a  single
+       The sequence (?# marks the start of a comment that continues up to  the
+       next  closing parenthesis. Nested parentheses are not permitted. If the
+       PCRE2_EXTENDED option is set, an unescaped # character also  introduces
+       a  comment,  which in this case continues to immediately after the next
+       newline character or character sequence in the pattern.  Which  charac-
+       ters  are  interpreted as newlines is controlled by an option passed to
+       the compiling function or by a special sequence at  the  start  of  the
+       pattern,  as  described  in  the section entitled "Newline conventions"
+       above. Note that the end of this type of comment is a  literal  newline
+       sequence  in  the  pattern; escape sequences that happen to represent a
+       newline  do  not  count.  For  example,  consider  this  pattern   when
+       PCRE2_EXTENDED  is  set,  and  the default newline convention (a single
        linefeed character) is in force:


          abc #comment \n still comment


-       On  encountering  the # character, pcre2_compile() skips along, looking
-       for a newline in the pattern. The sequence \n is still literal at  this
-       stage,  so  it does not terminate the comment. Only an actual character
+       On encountering the # character, pcre2_compile() skips  along,  looking
+       for  a newline in the pattern. The sequence \n is still literal at this
+       stage, so it does not terminate the comment. Only an  actual  character
        with the code value 0x0a (the default newline) does so.



RECURSIVE PATTERNS

-       Consider the problem of matching a string in parentheses, allowing  for
-       unlimited  nested  parentheses.  Without the use of recursion, the best
-       that can be done is to use a pattern that  matches  up  to  some  fixed
-       depth  of  nesting.  It  is not possible to handle an arbitrary nesting
+       Consider  the problem of matching a string in parentheses, allowing for
+       unlimited nested parentheses. Without the use of  recursion,  the  best
+       that  can  be  done  is  to use a pattern that matches up to some fixed
+       depth of nesting. It is not possible to  handle  an  arbitrary  nesting
        depth.


        For some time, Perl has provided a facility that allows regular expres-
-       sions  to recurse (amongst other things). It does this by interpolating
-       Perl code in the expression at run time, and the code can refer to  the
+       sions to recurse (amongst other things). It does this by  interpolating
+       Perl  code in the expression at run time, and the code can refer to the
        expression itself. A Perl pattern using code interpolation to solve the
        parentheses problem can be created like this:


@@ -8266,109 +8285,109 @@
        refers recursively to the pattern in which it appears.


        Obviously,  PCRE2  cannot  support  the  interpolation  of  Perl  code.
-       Instead, it supports special syntax for recursion of  the  entire  pat-
+       Instead,  it  supports  special syntax for recursion of the entire pat-
        tern, and also for individual subpattern recursion. After its introduc-
-       tion in PCRE1 and Python,  this  kind  of  recursion  was  subsequently
+       tion  in  PCRE1  and  Python,  this  kind of recursion was subsequently
        introduced into Perl at release 5.10.


-       A  special  item  that consists of (? followed by a number greater than
-       zero and a closing parenthesis is a recursive subroutine  call  of  the
-       subpattern  of  the  given  number, provided that it occurs inside that
-       subpattern. (If not, it is a non-recursive subroutine  call,  which  is
-       described  in  the  next  section.)  The special item (?R) or (?0) is a
+       A special item that consists of (? followed by a  number  greater  than
+       zero  and  a  closing parenthesis is a recursive subroutine call of the
+       subpattern of the given number, provided that  it  occurs  inside  that
+       subpattern.  (If  not,  it is a non-recursive subroutine call, which is
+       described in the next section.) The special item  (?R)  or  (?0)  is  a
        recursive call of the entire regular expression.


-       This PCRE2 pattern solves the nested parentheses  problem  (assume  the
+       This  PCRE2  pattern  solves the nested parentheses problem (assume the
        PCRE2_EXTENDED option is set so that white space is ignored):


          \( ( [^()]++ | (?R) )* \)


-       First  it matches an opening parenthesis. Then it matches any number of
-       substrings which can either be a  sequence  of  non-parentheses,  or  a
-       recursive  match  of the pattern itself (that is, a correctly parenthe-
+       First it matches an opening parenthesis. Then it matches any number  of
+       substrings  which  can  either  be  a sequence of non-parentheses, or a
+       recursive match of the pattern itself (that is, a  correctly  parenthe-
        sized substring).  Finally there is a closing parenthesis. Note the use
        of a possessive quantifier to avoid backtracking into sequences of non-
        parentheses.


-       If this were part of a larger pattern, you would not  want  to  recurse
+       If  this  were  part of a larger pattern, you would not want to recurse
        the entire pattern, so instead you could use this:


          ( \( ( [^()]++ | (?1) )* \) )


-       We  have  put the pattern into parentheses, and caused the recursion to
+       We have put the pattern into parentheses, and caused the  recursion  to
        refer to them instead of the whole pattern.


-       In a larger pattern,  keeping  track  of  parenthesis  numbers  can  be
-       tricky.  This is made easier by the use of relative references. Instead
+       In  a  larger  pattern,  keeping  track  of  parenthesis numbers can be
+       tricky. This is made easier by the use of relative references.  Instead
        of (?1) in the pattern above you can write (?-2) to refer to the second
-       most  recently  opened  parentheses  preceding  the recursion. In other
-       words, a negative number counts capturing  parentheses  leftwards  from
+       most recently opened parentheses  preceding  the  recursion.  In  other
+       words,  a  negative  number counts capturing parentheses leftwards from
        the point at which it is encountered.


        Be aware however, that if duplicate subpattern numbers are in use, rel-
-       ative references refer to the earliest subpattern with the  appropriate
+       ative  references refer to the earliest subpattern with the appropriate
        number. Consider, for example:


          (?|(a)|(b)) (c) (?-2)


-       The  first  two  capturing  groups (a) and (b) are both numbered 1, and
-       group (c) is number 2. When the reference  (?-2)  is  encountered,  the
+       The first two capturing groups (a) and (b) are  both  numbered  1,  and
+       group  (c)  is  number  2. When the reference (?-2) is encountered, the
        second most recently opened parentheses has the number 1, but it is the
-       first such group (the (a) group) to which the  recursion  refers.  This
-       would  be  the  same  if  an absolute reference (?1) was used. In other
-       words, relative references are just a shorthand for computing  a  group
+       first  such  group  (the (a) group) to which the recursion refers. This
+       would be the same if an absolute reference  (?1)  was  used.  In  other
+       words,  relative  references are just a shorthand for computing a group
        number.


-       It  is  also  possible  to refer to subsequently opened parentheses, by
-       writing references such as (?+2). However, these  cannot  be  recursive
-       because  the  reference  is  not inside the parentheses that are refer-
-       enced. They are always non-recursive subroutine calls, as described  in
+       It is also possible to refer to  subsequently  opened  parentheses,  by
+       writing  references  such  as (?+2). However, these cannot be recursive
+       because the reference is not inside the  parentheses  that  are  refer-
+       enced.  They are always non-recursive subroutine calls, as described in
        the next section.


-       An  alternative  approach  is to use named parentheses. The Perl syntax
-       for this is (?&name); PCRE1's earlier syntax  (?P>name)  is  also  sup-
+       An alternative approach is to use named parentheses.  The  Perl  syntax
+       for  this  is  (?&name);  PCRE1's earlier syntax (?P>name) is also sup-
        ported. We could rewrite the above example as follows:


          (?<pn> \( ( [^()]++ | (?&pn) )* \) )


-       If  there  is more than one subpattern with the same name, the earliest
+       If there is more than one subpattern with the same name,  the  earliest
        one is used.


        The example pattern that we have been looking at contains nested unlim-
-       ited  repeats,  and  so the use of a possessive quantifier for matching
-       strings of non-parentheses is important when applying  the  pattern  to
+       ited repeats, and so the use of a possessive  quantifier  for  matching
+       strings  of  non-parentheses  is important when applying the pattern to
        strings that do not match. For example, when this pattern is applied to


          (aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa()


-       it  yields  "no  match" quickly. However, if a possessive quantifier is
-       not used, the match runs for a very long time indeed because there  are
-       so  many  different  ways the + and * repeats can carve up the subject,
+       it yields "no match" quickly. However, if a  possessive  quantifier  is
+       not  used, the match runs for a very long time indeed because there are
+       so many different ways the + and * repeats can carve  up  the  subject,
        and all have to be tested before failure can be reported.


-       At the end of a match, the values of capturing  parentheses  are  those
-       from  the outermost level. If you want to obtain intermediate values, a
+       At  the  end  of a match, the values of capturing parentheses are those
+       from the outermost level. If you want to obtain intermediate values,  a
        callout function can be used (see below and the pcre2callout documenta-
        tion). If the pattern above is matched against


          (ab(cd)ef)


-       the  value  for  the  inner capturing parentheses (numbered 2) is "ef",
-       which is the last value taken on at the top level. If a capturing  sub-
-       pattern  is  not  matched at the top level, its final captured value is
-       unset, even if it was (temporarily) set at a deeper  level  during  the
+       the value for the inner capturing parentheses  (numbered  2)  is  "ef",
+       which  is the last value taken on at the top level. If a capturing sub-
+       pattern is not matched at the top level, its final  captured  value  is
+       unset,  even  if  it was (temporarily) set at a deeper level during the
        matching process.


-       Do  not  confuse  the (?R) item with the condition (R), which tests for
-       recursion.  Consider this pattern, which matches text in  angle  brack-
-       ets,  allowing for arbitrary nesting. Only digits are allowed in nested
-       brackets (that is, when recursing), whereas any characters are  permit-
+       Do not confuse the (?R) item with the condition (R),  which  tests  for
+       recursion.   Consider  this pattern, which matches text in angle brack-
+       ets, allowing for arbitrary nesting. Only digits are allowed in  nested
+       brackets  (that is, when recursing), whereas any characters are permit-
        ted at the outer level.


          < (?: (?(R) \d++  | [^<>]*+) | (?R)) * >


-       In  this  pattern, (?(R) is the start of a conditional subpattern, with
-       two different alternatives for the recursive and  non-recursive  cases.
+       In this pattern, (?(R) is the start of a conditional  subpattern,  with
+       two  different  alternatives for the recursive and non-recursive cases.
        The (?R) item is the actual recursive call.


    Differences in recursion processing between PCRE2 and Perl
@@ -8375,64 +8394,64 @@


        Some former differences between PCRE2 and Perl no longer exist.


-       Before  release 10.30, recursion processing in PCRE2 differed from Perl
-       in that a recursive subpattern call was always  treated  as  an  atomic
-       group.  That is, once it had matched some of the subject string, it was
-       never re-entered, even if it contained untried alternatives  and  there
-       was  a  subsequent matching failure. (Historical note: PCRE implemented
+       Before release 10.30, recursion processing in PCRE2 differed from  Perl
+       in  that  a  recursive  subpattern call was always treated as an atomic
+       group. That is, once it had matched some of the subject string, it  was
+       never  re-entered,  even if it contained untried alternatives and there
+       was a subsequent matching failure. (Historical note:  PCRE  implemented
        recursion before Perl did.)


-       Starting with release 10.30, recursive subroutine calls are  no  longer
+       Starting  with  release 10.30, recursive subroutine calls are no longer
        treated as atomic. That is, they can be re-entered to try unused alter-
-       natives if there is a matching failure later in the  pattern.  This  is
-       now  compatible  with the way Perl works. If you want a subroutine call
+       natives  if  there  is a matching failure later in the pattern. This is
+       now compatible with the way Perl works. If you want a  subroutine  call
        to be atomic, you must explicitly enclose it in an atomic group.


-       Supporting backtracking into recursions  simplifies  certain  types  of
+       Supporting  backtracking  into  recursions  simplifies certain types of
        recursive  pattern.  For  example,  this  pattern  matches  palindromic
        strings:


          ^((.)(?1)\2|.?)$


-       The second branch in the group matches a single  central  character  in
-       the  palindrome  when there are an odd number of characters, or nothing
-       when there are an even number of characters, but in order  to  work  it
-       has  to  be  able  to  try the second case when the rest of the pattern
+       The  second  branch  in the group matches a single central character in
+       the palindrome when there are an odd number of characters,  or  nothing
+       when  there  are  an even number of characters, but in order to work it
+       has to be able to try the second case when  the  rest  of  the  pattern
        match fails. If you want to match typical palindromic phrases, the pat-
-       tern  has  to  ignore  all  non-word characters, which can be done like
+       tern has to ignore all non-word characters,  which  can  be  done  like
        this:


          ^\W*+((.)\W*+(?1)\W*+\2|\W*+.?)\W*+$


-       If run with the PCRE2_CASELESS option,  this  pattern  matches  phrases
-       such  as "A man, a plan, a canal: Panama!". Note the use of the posses-
-       sive quantifier *+ to avoid backtracking  into  sequences  of  non-word
+       If  run  with  the  PCRE2_CASELESS option, this pattern matches phrases
+       such as "A man, a plan, a canal: Panama!". Note the use of the  posses-
+       sive  quantifier  *+  to  avoid backtracking into sequences of non-word
        characters. Without this, PCRE2 takes a great deal longer (ten times or
-       more) to match typical phrases, and Perl takes so long that  you  think
+       more)  to  match typical phrases, and Perl takes so long that you think
        it has gone into a loop.


-       Another  way  in which PCRE2 and Perl used to differ in their recursion
-       processing is in the handling of captured  values.  Formerly  in  Perl,
-       when  a  subpattern  was called recursively or as a subpattern (see the
-       next section), it had no access to any values that were  captured  out-
-       side  the  recursion,  whereas in PCRE2 these values can be referenced.
+       Another way in which PCRE2 and Perl used to differ in  their  recursion
+       processing  is  in  the  handling of captured values. Formerly in Perl,
+       when a subpattern was called recursively or as a  subpattern  (see  the
+       next  section),  it had no access to any values that were captured out-
+       side the recursion, whereas in PCRE2 these values  can  be  referenced.
        Consider this pattern:


          ^(.)(\1|a(?2))


-       This pattern matches "bab". The first capturing parentheses match  "b",
+       This  pattern matches "bab". The first capturing parentheses match "b",
        then in the second group, when the backreference \1 fails to match "b",
        the second alternative matches "a" and then recurses. In the recursion,
-       \1  does now match "b" and so the whole match succeeds. This match used
+       \1 does now match "b" and so the whole match succeeds. This match  used
        to fail in Perl, but in later versions (I tried 5.024) it now works.



SUBPATTERNS AS SUBROUTINES

-       If the syntax for a recursive subpattern call (either by number  or  by
-       name)  is  used outside the parentheses to which it refers, it operates
-       like a subroutine in a programming language. The called subpattern  may
-       be  defined  before or after the reference. A numbered reference can be
+       If  the  syntax for a recursive subpattern call (either by number or by
+       name) is used outside the parentheses to which it refers,  it  operates
+       like  a subroutine in a programming language. The called subpattern may
+       be defined before or after the reference. A numbered reference  can  be
        absolute or relative, as in these examples:


          (...(absolute)...)...(?2)...
@@ -8443,48 +8462,48 @@


          (sens|respons)e and \1ibility


-       matches "sense and sensibility" and "response and responsibility",  but
+       matches  "sense and sensibility" and "response and responsibility", but
        not "sense and responsibility". If instead the pattern


          (sens|respons)e and (?1)ibility


-       is  used, it does match "sense and responsibility" as well as the other
-       two strings. Another example is  given  in  the  discussion  of  DEFINE
+       is used, it does match "sense and responsibility" as well as the  other
+       two  strings.  Another  example  is  given  in the discussion of DEFINE
        above.


-       Like  recursions,  subroutine  calls  used to be treated as atomic, but
-       this changed at PCRE2 release 10.30, so  backtracking  into  subroutine
-       calls  can  now  occur. However, any capturing parentheses that are set
+       Like recursions, subroutine calls used to be  treated  as  atomic,  but
+       this  changed  at  PCRE2 release 10.30, so backtracking into subroutine
+       calls can now occur. However, any capturing parentheses  that  are  set
        during the subroutine call revert to their previous values afterwards.


-       Processing options such as case-independence are fixed when  a  subpat-
-       tern  is defined, so if it is used as a subroutine, such options cannot
+       Processing  options  such as case-independence are fixed when a subpat-
+       tern is defined, so if it is used as a subroutine, such options  cannot
        be changed for different calls. For example, consider this pattern:


          (abc)(?i:(?-1))


-       It matches "abcabc". It does not match "abcABC" because the  change  of
+       It  matches  "abcabc". It does not match "abcABC" because the change of
        processing option does not affect the called subpattern.



ONIGURUMA SUBROUTINE SYNTAX

-       For  compatibility with Oniguruma, the non-Perl syntax \g followed by a
+       For compatibility with Oniguruma, the non-Perl syntax \g followed by  a
        name or a number enclosed either in angle brackets or single quotes, is
-       an  alternative  syntax  for  referencing a subpattern as a subroutine,
-       possibly recursively. Here are two of the examples used above,  rewrit-
+       an alternative syntax for referencing a  subpattern  as  a  subroutine,
+       possibly  recursively. Here are two of the examples used above, rewrit-
        ten using this syntax:


          (?<pn> \( ( (?>[^()]+) | \g<pn> )* \) )
          (sens|respons)e and \g'1'ibility


-       PCRE2  supports an extension to Oniguruma: if a number is preceded by a
+       PCRE2 supports an extension to Oniguruma: if a number is preceded by  a
        plus or a minus sign it is taken as a relative reference. For example:


          (abc)(?i:\g<-1>)


-       Note that \g{...} (Perl syntax) and \g<...> (Oniguruma syntax) are  not
-       synonymous.  The  former is a backreference; the latter is a subroutine
+       Note  that \g{...} (Perl syntax) and \g<...> (Oniguruma syntax) are not
+       synonymous. The former is a backreference; the latter is  a  subroutine
        call.



@@ -8491,54 +8510,54 @@
CALLOUTS

        Perl has a feature whereby using the sequence (?{...}) causes arbitrary
-       Perl  code to be obeyed in the middle of matching a regular expression.
+       Perl code to be obeyed in the middle of matching a regular  expression.
        This makes it possible, amongst other things, to extract different sub-
        strings that match the same pair of parentheses when there is a repeti-
        tion.


-       PCRE2 provides a similar feature, but of course it  cannot  obey  arbi-
-       trary  Perl  code. The feature is called "callout". The caller of PCRE2
-       provides an external function by putting its entry  point  in  a  match
-       context  using  the function pcre2_set_callout(), and then passing that
-       context to pcre2_match() or pcre2_dfa_match(). If no match  context  is
+       PCRE2  provides  a  similar feature, but of course it cannot obey arbi-
+       trary Perl code. The feature is called "callout". The caller  of  PCRE2
+       provides  an  external  function  by putting its entry point in a match
+       context using the function pcre2_set_callout(), and then  passing  that
+       context  to  pcre2_match() or pcre2_dfa_match(). If no match context is
        passed, or if the callout entry point is set to NULL, callouts are dis-
        abled.


-       Within a regular expression, (?C<arg>) indicates a point at  which  the
-       external  function  is  to  be  called. There are two kinds of callout:
-       those with a numerical argument and those with a string argument.  (?C)
-       on  its  own with no argument is treated as (?C0). A numerical argument
-       allows the  application  to  distinguish  between  different  callouts.
-       String  arguments  were added for release 10.20 to make it possible for
-       script languages that use PCRE2 to embed short scripts within  patterns
+       Within  a  regular expression, (?C<arg>) indicates a point at which the
+       external function is to be called. There  are  two  kinds  of  callout:
+       those  with a numerical argument and those with a string argument. (?C)
+       on its own with no argument is treated as (?C0). A  numerical  argument
+       allows  the  application  to  distinguish  between  different callouts.
+       String arguments were added for release 10.20 to make it  possible  for
+       script  languages that use PCRE2 to embed short scripts within patterns
        in a similar way to Perl.


        During matching, when PCRE2 reaches a callout point, the external func-
-       tion is called. It is provided with the number or  string  argument  of
-       the  callout, the position in the pattern, and one item of data that is
+       tion  is  called.  It is provided with the number or string argument of
+       the callout, the position in the pattern, and one item of data that  is
        also set in the match block. The callout function may cause matching to
        proceed, to backtrack, or to fail.


-       By  default,  PCRE2  implements  a  number of optimizations at matching
-       time, and one side-effect is that sometimes callouts  are  skipped.  If
-       you  need all possible callouts to happen, you need to set options that
-       disable the relevant optimizations. More details, including a  complete
-       description  of  the programming interface to the callout function, are
+       By default, PCRE2 implements a  number  of  optimizations  at  matching
+       time,  and  one  side-effect is that sometimes callouts are skipped. If
+       you need all possible callouts to happen, you need to set options  that
+       disable  the relevant optimizations. More details, including a complete
+       description of the programming interface to the callout  function,  are
        given in the pcre2callout documentation.


    Callouts with numerical arguments


-       If you just want to have  a  means  of  identifying  different  callout
-       points,  put  a  number  less than 256 after the letter C. For example,
+       If  you  just  want  to  have  a means of identifying different callout
+       points, put a number less than 256 after the  letter  C.  For  example,
        this pattern has two callout points:


          (?C1)abc(?C2)def


-       If the PCRE2_AUTO_CALLOUT flag is passed to pcre2_compile(),  numerical
-       callouts  are  automatically installed before each item in the pattern.
-       They are all numbered 255. If there is a conditional group in the  pat-
+       If  the PCRE2_AUTO_CALLOUT flag is passed to pcre2_compile(), numerical
+       callouts are automatically installed before each item in  the  pattern.
+       They  are all numbered 255. If there is a conditional group in the pat-
        tern whose condition is an assertion, an additional callout is inserted
-       just before the condition. An explicit callout may also be set at  this
+       just  before the condition. An explicit callout may also be set at this
        position, as in this example:


          (?(?C9)(?=a)abc|def)
@@ -8548,60 +8567,60 @@


    Callouts with string arguments


-       A delimited string may be used instead of a number as a  callout  argu-
-       ment.  The  starting  delimiter  must be one of ` ' " ^ % # $ { and the
+       A  delimited  string may be used instead of a number as a callout argu-
+       ment. The starting delimiter must be one of ` ' " ^ % #  $  {  and  the
        ending delimiter is the same as the start, except for {, where the end-
-       ing  delimiter  is  }.  If  the  ending  delimiter is needed within the
+       ing delimiter is }. If  the  ending  delimiter  is  needed  within  the
        string, it must be doubled. For example:


          (?C'ab ''c'' d')xyz(?C{any text})pqr


-       The doubling is removed before the string  is  passed  to  the  callout
+       The  doubling  is  removed  before  the string is passed to the callout
        function.



BACKTRACKING CONTROL

-       There  are  a  number  of  special "Backtracking Control Verbs" (to use
-       Perl's terminology) that modify the behaviour  of  backtracking  during
-       matching.  They are generally of the form (*VERB) or (*VERB:NAME). Some
-       verbs take either form,  possibly  behaving  differently  depending  on
+       There are a number of special  "Backtracking  Control  Verbs"  (to  use
+       Perl's  terminology)  that  modify the behaviour of backtracking during
+       matching. They are generally of the form (*VERB) or (*VERB:NAME).  Some
+       verbs  take  either  form,  possibly  behaving differently depending on
        whether or not a name is present.


-       By  default,  for  compatibility  with  Perl, a name is any sequence of
+       By default, for compatibility with Perl, a  name  is  any  sequence  of
        characters that does not include a closing parenthesis. The name is not
-       processed  in  any  way,  and  it  is not possible to include a closing
-       parenthesis  in  the  name.   This  can  be  changed  by  setting   the
-       PCRE2_ALT_VERBNAMES  option,  but the result is no longer Perl-compati-
+       processed in any way, and it is  not  possible  to  include  a  closing
+       parenthesis   in  the  name.   This  can  be  changed  by  setting  the
+       PCRE2_ALT_VERBNAMES option, but the result is no  longer  Perl-compati-
        ble.


-       When PCRE2_ALT_VERBNAMES is set, backslash  processing  is  applied  to
-       verb  names  and  only  an unescaped closing parenthesis terminates the
-       name. However, the only backslash items that are permitted are \Q,  \E,
-       and  sequences such as \x{100} that define character code points. Char-
+       When  PCRE2_ALT_VERBNAMES  is  set,  backslash processing is applied to
+       verb names and only an unescaped  closing  parenthesis  terminates  the
+       name.  However, the only backslash items that are permitted are \Q, \E,
+       and sequences such as \x{100} that define character code points.  Char-
        acter type escapes such as \d are faulted.


        A closing parenthesis can be included in a name either as \) or between
-       \Q  and  \E. In addition to backslash processing, if the PCRE2_EXTENDED
-       option is also set, unescaped whitespace in verb names is skipped,  and
-       #-comments  are  recognized,  exactly  as  in  the rest of the pattern.
+       \Q and \E. In addition to backslash processing, if  the  PCRE2_EXTENDED
+       option  is also set, unescaped whitespace in verb names is skipped, and
+       #-comments are recognized, exactly as  in  the  rest  of  the  pattern.
        PCRE2_EXTENDED does not affect verb names unless PCRE2_ALT_VERBNAMES is
        also set.


-       The  maximum  length of a name is 255 in the 8-bit library and 65535 in
-       the 16-bit and 32-bit libraries. If the name is empty, that is, if  the
-       closing  parenthesis immediately follows the colon, the effect is as if
+       The maximum length of a name is 255 in the 8-bit library and  65535  in
+       the  16-bit and 32-bit libraries. If the name is empty, that is, if the
+       closing parenthesis immediately follows the colon, the effect is as  if
        the colon were not there. Any number of these verbs may occur in a pat-
        tern.


-       Since  these  verbs  are  specifically related to backtracking, most of
-       them can be used only when the pattern is to be matched using the  tra-
+       Since these verbs are specifically related  to  backtracking,  most  of
+       them  can be used only when the pattern is to be matched using the tra-
        ditional matching function, because that uses a backtracking algorithm.
-       With the exception of (*FAIL), which behaves like  a  failing  negative
+       With  the  exception  of (*FAIL), which behaves like a failing negative
        assertion, the backtracking control verbs cause an error if encountered
        by the DFA matching function.


-       The behaviour of these verbs in repeated  groups,  assertions,  and  in
+       The  behaviour  of  these  verbs in repeated groups, assertions, and in
        subpatterns called as subroutines (whether or not recursively) is docu-
        mented below.


@@ -8609,16 +8628,16 @@

        PCRE2 contains some optimizations that are used to speed up matching by
        running some checks at the start of each match attempt. For example, it
-       may know the minimum length of matching subject, or that  a  particular
+       may  know  the minimum length of matching subject, or that a particular
        character must be present. When one of these optimizations bypasses the
-       running of a match,  any  included  backtracking  verbs  will  not,  of
+       running  of  a  match,  any  included  backtracking  verbs will not, of
        course, be processed. You can suppress the start-of-match optimizations
-       by setting the PCRE2_NO_START_OPTIMIZE option when  calling  pcre2_com-
-       pile(),  or by starting the pattern with (*NO_START_OPT). There is more
+       by  setting  the PCRE2_NO_START_OPTIMIZE option when calling pcre2_com-
+       pile(), or by starting the pattern with (*NO_START_OPT). There is  more
        discussion of this option in the section entitled "Compiling a pattern"
        in the pcre2api documentation.


-       Experiments  with  Perl  suggest that it too has similar optimizations,
+       Experiments with Perl suggest that it too  has  similar  optimizations,
        and like PCRE2, turning them off can change the result of a match.


    Verbs that act immediately
@@ -8627,63 +8646,63 @@


           (*ACCEPT) or (*ACCEPT:NAME)


-       This verb causes the match to end successfully, skipping the  remainder
-       of  the pattern. However, when it is inside a subpattern that is called
-       as a subroutine, only that subpattern is ended  successfully.  Matching
+       This  verb causes the match to end successfully, skipping the remainder
+       of the pattern. However, when it is inside a subpattern that is  called
+       as  a  subroutine, only that subpattern is ended successfully. Matching
        then continues at the outer level. If (*ACCEPT) in triggered in a posi-
-       tive assertion, the assertion succeeds; in a  negative  assertion,  the
+       tive  assertion,  the  assertion succeeds; in a negative assertion, the
        assertion fails.


-       If  (*ACCEPT)  is inside capturing parentheses, the data so far is cap-
+       If (*ACCEPT) is inside capturing parentheses, the data so far  is  cap-
        tured. For example:


          A((?:A|B(*ACCEPT)|C)D)


-       This matches "AB", "AAD", or "ACD"; when it matches "AB", "B"  is  cap-
+       This  matches  "AB", "AAD", or "ACD"; when it matches "AB", "B" is cap-
        tured by the outer parentheses.


          (*FAIL) or (*FAIL:NAME)


-       This  verb causes a matching failure, forcing backtracking to occur. It
-       may be abbreviated to (*F). It is equivalent  to  (?!)  but  easier  to
+       This verb causes a matching failure, forcing backtracking to occur.  It
+       may  be  abbreviated  to  (*F).  It is equivalent to (?!) but easier to
        read. The Perl documentation notes that it is probably useful only when
        combined with (?{}) or (??{}). Those are, of course, Perl features that
-       are  not  present  in PCRE2. The nearest equivalent is the callout fea-
+       are not present in PCRE2. The nearest equivalent is  the  callout  fea-
        ture, as for example in this pattern:


          a+(?C)(*FAIL)


-       A match with the string "aaaa" always fails, but the callout  is  taken
+       A  match  with the string "aaaa" always fails, but the callout is taken
        before each backtrack happens (in this example, 10 times).


-       (*ACCEPT:NAME)   and   (*FAIL:NAME)   behave   exactly   the   same  as
+       (*ACCEPT:NAME)  and   (*FAIL:NAME)   behave   exactly   the   same   as
        (*MARK:NAME)(*ACCEPT) and (*MARK:NAME)(*FAIL), respectively.


    Recording which path was taken


-       There is one verb whose main purpose  is  to  track  how  a  match  was
-       arrived  at,  though  it  also  has a secondary use in conjunction with
+       There  is  one  verb  whose  main  purpose  is to track how a match was
+       arrived at, though it also has a  secondary  use  in  conjunction  with
        advancing the match starting point (see (*SKIP) below).


          (*MARK:NAME) or (*:NAME)


-       A name is always  required  with  this  verb.  There  may  be  as  many
-       instances  of  (*MARK) as you like in a pattern, and their names do not
+       A  name  is  always  required  with  this  verb.  There  may be as many
+       instances of (*MARK) as you like in a pattern, and their names  do  not
        have to be unique.


        When a match succeeds, the name of the last-encountered (*MARK:NAME) on
        the matching path is passed back to the caller as described in the sec-
        tion entitled "Other information about the match" in the pcre2api docu-
-       mentation.  This  applies  to all instances of (*MARK), including those
-       inside assertions and atomic groups. (There are  differences  in  those
-       cases  when  (*MARK)  is  used in conjunction with (*SKIP) as described
+       mentation. This applies to all instances of  (*MARK),  including  those
+       inside  assertions  and  atomic groups. (There are differences in those
+       cases when (*MARK) is used in conjunction  with  (*SKIP)  as  described
        below.)


-       As well as (*MARK), the (*COMMIT), (*PRUNE) and (*THEN) verbs may  have
-       associated  NAME  arguments.  Whichever is last on the matching path is
+       As  well as (*MARK), the (*COMMIT), (*PRUNE) and (*THEN) verbs may have
+       associated NAME arguments. Whichever is last on the  matching  path  is
        passed back. See below for more details of these other verbs.


-       Here is an example of  pcre2test  output,  where  the  "mark"  modifier
+       Here  is  an  example  of  pcre2test  output, where the "mark" modifier
        requests the retrieval and outputting of (*MARK) data:


            re> /X(*MARK:A)Y|X(*MARK:B)Z/mark
@@ -8695,16 +8714,16 @@
          MK: B


        The (*MARK) name is tagged with "MK:" in this output, and in this exam-
-       ple it indicates which of the two alternatives matched. This is a  more
-       efficient  way of obtaining this information than putting each alterna-
+       ple  it indicates which of the two alternatives matched. This is a more
+       efficient way of obtaining this information than putting each  alterna-
        tive in its own capturing parentheses.


-       If a verb with a name is encountered in a positive  assertion  that  is
-       true,  the  name  is recorded and passed back if it is the last-encoun-
+       If  a  verb  with a name is encountered in a positive assertion that is
+       true, the name is recorded and passed back if it  is  the  last-encoun-
        tered. This does not happen for negative assertions or failing positive
        assertions.


-       After  a  partial match or a failed match, the last encountered name in
+       After a partial match or a failed match, the last encountered  name  in
        the entire match process is returned. For example:


            re> /X(*MARK:A)Y|X(*MARK:B)Z/mark
@@ -8711,38 +8730,38 @@
          data> XP
          No match, mark = B


-       Note that in this unanchored example the  mark  is  retained  from  the
+       Note  that  in  this  unanchored  example the mark is retained from the
        match attempt that started at the letter "X" in the subject. Subsequent
        match attempts starting at "P" and then with an empty string do not get
        as far as the (*MARK) item, but nevertheless do not reset it.


-       If  you  are  interested  in  (*MARK)  values after failed matches, you
-       should probably set the PCRE2_NO_START_OPTIMIZE option (see  above)  to
+       If you are interested in  (*MARK)  values  after  failed  matches,  you
+       should  probably  set the PCRE2_NO_START_OPTIMIZE option (see above) to
        ensure that the match is always attempted.


    Verbs that act after backtracking


        The following verbs do nothing when they are encountered. Matching con-
-       tinues with what follows, but if there is a subsequent  match  failure,
-       causing  a  backtrack  to the verb, a failure is forced. That is, back-
-       tracking cannot pass to the left of the  verb.  However,  when  one  of
+       tinues  with  what follows, but if there is a subsequent match failure,
+       causing a backtrack to the verb, a failure is forced.  That  is,  back-
+       tracking  cannot  pass  to  the  left of the verb. However, when one of
        these verbs appears inside an atomic group or in a lookaround assertion
-       that is true, its effect is confined to that group,  because  once  the
-       group  has been matched, there is never any backtracking into it. Back-
+       that  is  true,  its effect is confined to that group, because once the
+       group has been matched, there is never any backtracking into it.  Back-
        tracking from beyond an assertion or an atomic group ignores the entire
        group, and seeks a preceeding backtracking point.


-       These  verbs  differ  in exactly what kind of failure occurs when back-
-       tracking reaches them. The behaviour described below  is  what  happens
-       when  the  verb is not in a subroutine or an assertion. Subsequent sec-
+       These verbs differ in exactly what kind of failure  occurs  when  back-
+       tracking  reaches  them.  The behaviour described below is what happens
+       when the verb is not in a subroutine or an assertion.  Subsequent  sec-
        tions cover these special cases.


          (*COMMIT) or (*COMMIT:NAME)


-       This verb causes the whole match to fail outright if there is  a  later
+       This  verb  causes the whole match to fail outright if there is a later
        matching failure that causes backtracking to reach it. Even if the pat-
-       tern is unanchored, no further attempts to find a  match  by  advancing
-       the  starting  point  take place. If (*COMMIT) is the only backtracking
+       tern  is  unanchored,  no further attempts to find a match by advancing
+       the starting point take place. If (*COMMIT) is  the  only  backtracking
        verb that is encountered, once it has been passed pcre2_match() is com-
        mitted to finding a match at the current starting point, or not at all.
        For example:
@@ -8749,22 +8768,22 @@


          a+(*COMMIT)b


-       This matches "xxaab" but not "aacaab". It can be thought of as  a  kind
+       This  matches  "xxaab" but not "aacaab". It can be thought of as a kind
        of dynamic anchor, or "I've started, so I must finish."


-       The  behaviour  of (*COMMIT:NAME) is not the same as (*MARK:NAME)(*COM-
-       MIT). It is like (*MARK:NAME) in that the name is remembered for  pass-
-       ing  back  to the caller. However, (*SKIP:NAME) searches only for names
-       set with  (*MARK),  ignoring  those  set  by  (*COMMIT),  (*PRUNE)  and
+       The behaviour of (*COMMIT:NAME) is not the same  as  (*MARK:NAME)(*COM-
+       MIT).  It is like (*MARK:NAME) in that the name is remembered for pass-
+       ing back to the caller. However, (*SKIP:NAME) searches only  for  names
+       set  with  (*MARK),  ignoring  those  set  by  (*COMMIT),  (*PRUNE) and
        (*THEN).


-       If  there  is more than one backtracking verb in a pattern, a different
-       one that follows (*COMMIT) may be triggered first,  so  merely  passing
+       If there is more than one backtracking verb in a pattern,  a  different
+       one  that  follows  (*COMMIT) may be triggered first, so merely passing
        (*COMMIT) during a match does not always guarantee that a match must be
        at this starting point.


-       Note that (*COMMIT) at the start of a pattern is not  the  same  as  an
-       anchor,  unless PCRE2's start-of-match optimizations are turned off, as
+       Note  that  (*COMMIT)  at  the start of a pattern is not the same as an
+       anchor, unless PCRE2's start-of-match optimizations are turned off,  as
        shown in this output from pcre2test:


            re> /(*COMMIT)abc/
@@ -8775,63 +8794,63 @@
          data> xyzabc
          No match


-       For the first pattern, PCRE2 knows that any match must start with  "a",
-       so  the optimization skips along the subject to "a" before applying the
-       pattern to the first set of data. The match attempt then succeeds.  The
-       second  pattern disables the optimization that skips along to the first
-       character. The pattern is now applied  starting  at  "x",  and  so  the
-       (*COMMIT)  causes  the  match to fail without trying any other starting
+       For  the first pattern, PCRE2 knows that any match must start with "a",
+       so the optimization skips along the subject to "a" before applying  the
+       pattern  to the first set of data. The match attempt then succeeds. The
+       second pattern disables the optimization that skips along to the  first
+       character.  The  pattern  is  now  applied  starting at "x", and so the
+       (*COMMIT) causes the match to fail without trying  any  other  starting
        points.


          (*PRUNE) or (*PRUNE:NAME)


-       This verb causes the match to fail at the current starting position  in
+       This  verb causes the match to fail at the current starting position in
        the subject if there is a later matching failure that causes backtrack-
-       ing to reach it. If the pattern is unanchored, the  normal  "bumpalong"
-       advance  to  the next starting character then happens. Backtracking can
-       occur as usual to the left of (*PRUNE), before it is reached,  or  when
-       matching  to  the  right  of  (*PRUNE), but if there is no match to the
-       right, backtracking cannot cross (*PRUNE). In simple cases, the use  of
-       (*PRUNE)  is just an alternative to an atomic group or possessive quan-
+       ing  to  reach it. If the pattern is unanchored, the normal "bumpalong"
+       advance to the next starting character then happens.  Backtracking  can
+       occur  as  usual to the left of (*PRUNE), before it is reached, or when
+       matching to the right of (*PRUNE), but if there  is  no  match  to  the
+       right,  backtracking cannot cross (*PRUNE). In simple cases, the use of
+       (*PRUNE) is just an alternative to an atomic group or possessive  quan-
        tifier, but there are some uses of (*PRUNE) that cannot be expressed in
-       any  other  way. In an anchored pattern (*PRUNE) has the same effect as
+       any other way. In an anchored pattern (*PRUNE) has the same  effect  as
        (*COMMIT).


        The behaviour of (*PRUNE:NAME) is not the same as (*MARK:NAME)(*PRUNE).
        It is like (*MARK:NAME) in that the name is remembered for passing back
-       to the caller. However, (*SKIP:NAME) searches only for names  set  with
+       to  the  caller. However, (*SKIP:NAME) searches only for names set with
        (*MARK), ignoring those set by (*COMMIT), (*PRUNE) or (*THEN).


          (*SKIP)


-       This  verb, when given without a name, is like (*PRUNE), except that if
-       the pattern is unanchored, the "bumpalong" advance is not to  the  next
+       This verb, when given without a name, is like (*PRUNE), except that  if
+       the  pattern  is unanchored, the "bumpalong" advance is not to the next
        character, but to the position in the subject where (*SKIP) was encoun-
-       tered. (*SKIP) signifies that whatever text was matched leading  up  to
-       it  cannot  be part of a successful match if there is a later mismatch.
+       tered.  (*SKIP)  signifies that whatever text was matched leading up to
+       it cannot be part of a successful match if there is a  later  mismatch.
        Consider:


          a+(*SKIP)b


-       If the subject is "aaaac...",  after  the  first  match  attempt  fails
-       (starting  at  the  first  character in the string), the starting point
+       If  the  subject  is  "aaaac...",  after  the first match attempt fails
+       (starting at the first character in the  string),  the  starting  point
        skips on to start the next attempt at "c". Note that a possessive quan-
-       tifer  does not have the same effect as this example; although it would
-       suppress backtracking  during  the  first  match  attempt,  the  second
-       attempt  would  start at the second character instead of skipping on to
+       tifer does not have the same effect as this example; although it  would
+       suppress  backtracking  during  the  first  match  attempt,  the second
+       attempt would start at the second character instead of skipping  on  to
        "c".


          (*SKIP:NAME)


-       When (*SKIP) has an associated name, its behaviour  is  modified.  When
-       such  a  (*SKIP) is triggered, the previous path through the pattern is
-       searched for the most recent (*MARK) that has the same name. If one  is
-       found,  the  "bumpalong" advance is to the subject position that corre-
-       sponds to that (*MARK) instead of to where (*SKIP) was encountered.  If
+       When  (*SKIP)  has  an associated name, its behaviour is modified. When
+       such a (*SKIP) is triggered, the previous path through the  pattern  is
+       searched  for the most recent (*MARK) that has the same name. If one is
+       found, the "bumpalong" advance is to the subject position  that  corre-
+       sponds  to that (*MARK) instead of to where (*SKIP) was encountered. If
        no (*MARK) with a matching name is found, the (*SKIP) is ignored.


-       The  search  for a (*MARK) name uses the normal backtracking mechanism,
-       which means that it does not  see  (*MARK)  settings  that  are  inside
+       The search for a (*MARK) name uses the normal  backtracking  mechanism,
+       which  means  that  it  does  not  see (*MARK) settings that are inside
        atomic groups or assertions, because they are never re-entered by back-
        tracking. Compare the following pcre2test examples:


@@ -8845,106 +8864,106 @@
           0: b
           1: b


-       In the first example, the (*MARK) setting is in an atomic group, so  it
+       In  the first example, the (*MARK) setting is in an atomic group, so it
        is not seen when (*SKIP:X) triggers, causing the (*SKIP) to be ignored.
-       This allows the second branch of the pattern to be tried at  the  first
-       character  position.  In the second example, the (*MARK) setting is not
-       in an atomic group. This allows (*SKIP:X) to find the (*MARK)  when  it
+       This  allows  the second branch of the pattern to be tried at the first
+       character position.  In the second example, the (*MARK) setting is  not
+       in  an  atomic group. This allows (*SKIP:X) to find the (*MARK) when it
        backtracks, and this causes a new matching attempt to start at the sec-
-       ond character. This time, the (*MARK) is never seen  because  "a"  does
+       ond  character.  This  time, the (*MARK) is never seen because "a" does
        not match "b", so the matcher immediately jumps to the second branch of
        the pattern.


-       Note that (*SKIP:NAME) searches only for names set by (*MARK:NAME).  It
-       ignores   names  that  are  set  by  (*COMMIT:NAME),  (*PRUNE:NAME)  or
+       Note  that (*SKIP:NAME) searches only for names set by (*MARK:NAME). It
+       ignores  names  that  are  set  by  (*COMMIT:NAME),  (*PRUNE:NAME)   or
        (*THEN:NAME).


          (*THEN) or (*THEN:NAME)


-       This verb causes a skip to the next innermost  alternative  when  back-
-       tracking  reaches  it.  That  is,  it  cancels any further backtracking
-       within the current alternative. Its name  comes  from  the  observation
+       This  verb  causes  a skip to the next innermost alternative when back-
+       tracking reaches it. That  is,  it  cancels  any  further  backtracking
+       within  the  current  alternative.  Its name comes from the observation
        that it can be used for a pattern-based if-then-else block:


          ( COND1 (*THEN) FOO | COND2 (*THEN) BAR | COND3 (*THEN) BAZ ) ...


-       If  the COND1 pattern matches, FOO is tried (and possibly further items
-       after the end of the group if FOO succeeds); on  failure,  the  matcher
-       skips  to  the second alternative and tries COND2, without backtracking
-       into COND1. If that succeeds and BAR fails, COND3 is tried.  If  subse-
-       quently  BAZ fails, there are no more alternatives, so there is a back-
-       track to whatever came before the  entire  group.  If  (*THEN)  is  not
+       If the COND1 pattern matches, FOO is tried (and possibly further  items
+       after  the  end  of the group if FOO succeeds); on failure, the matcher
+       skips to the second alternative and tries COND2,  without  backtracking
+       into  COND1.  If that succeeds and BAR fails, COND3 is tried. If subse-
+       quently BAZ fails, there are no more alternatives, so there is a  back-
+       track  to  whatever  came  before  the  entire group. If (*THEN) is not
        inside an alternation, it acts like (*PRUNE).


-       The  behaviour  of (*THEN:NAME) is not the same as (*MARK:NAME)(*THEN).
+       The behaviour of (*THEN:NAME) is not the same  as  (*MARK:NAME)(*THEN).
        It is like (*MARK:NAME) in that the name is remembered for passing back
-       to  the  caller. However, (*SKIP:NAME) searches only for names set with
+       to the caller. However, (*SKIP:NAME) searches only for names  set  with
        (*MARK), ignoring those set by (*COMMIT), (*PRUNE) and (*THEN).


-       A subpattern that does not contain a | character is just a part of  the
-       enclosing  alternative;  it  is  not a nested alternation with only one
-       alternative. The effect of (*THEN) extends beyond such a subpattern  to
-       the  enclosing alternative. Consider this pattern, where A, B, etc. are
-       complex pattern fragments that do not contain any | characters at  this
+       A  subpattern that does not contain a | character is just a part of the
+       enclosing alternative; it is not a nested  alternation  with  only  one
+       alternative.  The effect of (*THEN) extends beyond such a subpattern to
+       the enclosing alternative. Consider this pattern, where A, B, etc.  are
+       complex  pattern fragments that do not contain any | characters at this
        level:


          A (B(*THEN)C) | D


-       If  A and B are matched, but there is a failure in C, matching does not
+       If A and B are matched, but there is a failure in C, matching does  not
        backtrack into A; instead it moves to the next alternative, that is, D.
-       However,  if the subpattern containing (*THEN) is given an alternative,
+       However, if the subpattern containing (*THEN) is given an  alternative,
        it behaves differently:


          A (B(*THEN)C | (*FAIL)) | D


-       The effect of (*THEN) is now confined to the inner subpattern. After  a
+       The  effect of (*THEN) is now confined to the inner subpattern. After a
        failure in C, matching moves to (*FAIL), which causes the whole subpat-
-       tern to fail because there are no more alternatives  to  try.  In  this
+       tern  to  fail  because  there are no more alternatives to try. In this
        case, matching does now backtrack into A.


-       Note  that  a  conditional  subpattern  is not considered as having two
-       alternatives, because only one is ever used.  In  other  words,  the  |
+       Note that a conditional subpattern is  not  considered  as  having  two
+       alternatives,  because  only  one  is  ever used. In other words, the |
        character in a conditional subpattern has a different meaning. Ignoring
        white space, consider:


          ^.*? (?(?=a) a | b(*THEN)c )


-       If the subject is "ba", this pattern does not  match.  Because  .*?  is
-       ungreedy,  it  initially  matches  zero characters. The condition (?=a)
-       then fails, the character "b" is matched,  but  "c"  is  not.  At  this
-       point,  matching does not backtrack to .*? as might perhaps be expected
-       from the presence of the | character.  The  conditional  subpattern  is
+       If  the  subject  is  "ba", this pattern does not match. Because .*? is
+       ungreedy, it initially matches zero  characters.  The  condition  (?=a)
+       then  fails,  the  character  "b"  is  matched, but "c" is not. At this
+       point, matching does not backtrack to .*? as might perhaps be  expected
+       from  the  presence  of  the | character. The conditional subpattern is
        part of the single alternative that comprises the whole pattern, and so
-       the match fails. (If there was a backtrack into  .*?,  allowing  it  to
+       the  match  fails.  (If  there was a backtrack into .*?, allowing it to
        match "b", the match would succeed.)


-       The  verbs just described provide four different "strengths" of control
+       The verbs just described provide four different "strengths" of  control
        when subsequent matching fails. (*THEN) is the weakest, carrying on the
-       match  at  the next alternative. (*PRUNE) comes next, failing the match
-       at the current starting position, but allowing an advance to  the  next
-       character  (for an unanchored pattern). (*SKIP) is similar, except that
+       match at the next alternative. (*PRUNE) comes next, failing  the  match
+       at  the  current starting position, but allowing an advance to the next
+       character (for an unanchored pattern). (*SKIP) is similar, except  that
        the advance may be more than one character. (*COMMIT) is the strongest,
        causing the entire match to fail.


    More than one backtracking verb


-       If  more  than  one  backtracking verb is present in a pattern, the one
-       that is backtracked onto first acts. For example,  consider  this  pat-
+       If more than one backtracking verb is present in  a  pattern,  the  one
+       that  is  backtracked  onto first acts. For example, consider this pat-
        tern, where A, B, etc. are complex pattern fragments:


          (A(*COMMIT)B(*THEN)C|ABD)


-       If  A matches but B fails, the backtrack to (*COMMIT) causes the entire
+       If A matches but B fails, the backtrack to (*COMMIT) causes the  entire
        match to fail. However, if A and B match, but C fails, the backtrack to
-       (*THEN)  causes  the next alternative (ABD) to be tried. This behaviour
-       is consistent, but is not always the same as Perl's. It means  that  if
-       two  or  more backtracking verbs appear in succession, all the the last
+       (*THEN) causes the next alternative (ABD) to be tried.  This  behaviour
+       is  consistent,  but is not always the same as Perl's. It means that if
+       two or more backtracking verbs appear in succession, all the  the  last
        of them has no effect. Consider this example:


          ...(*COMMIT)(*PRUNE)...


        If there is a matching failure to the right, backtracking onto (*PRUNE)
-       causes  it to be triggered, and its action is taken. There can never be
+       causes it to be triggered, and its action is taken. There can never  be
        a backtrack onto (*COMMIT).


    Backtracking verbs in repeated groups
@@ -8954,42 +8973,42 @@


          /(a(*COMMIT)b)+ac/


-       If  the  subject  is  "abac", Perl matches unless its optimizations are
-       disabled, but PCRE2 always fails because the (*COMMIT)  in  the  second
+       If the subject is "abac", Perl matches  unless  its  optimizations  are
+       disabled,  but  PCRE2  always fails because the (*COMMIT) in the second
        repeat of the group acts.


    Backtracking verbs in assertions


-       (*FAIL)  in any assertion has its normal effect: it forces an immediate
-       backtrack. The behaviour of the other  backtracking  verbs  depends  on
-       whether  or  not the assertion is standalone or acting as the condition
+       (*FAIL) in any assertion has its normal effect: it forces an  immediate
+       backtrack.  The  behaviour  of  the other backtracking verbs depends on
+       whether or not the assertion is standalone or acting as  the  condition
        in a conditional subpattern.


-       (*ACCEPT) in a standalone positive assertion causes  the  assertion  to
-       succeed  without any further processing; captured strings and a (*MARK)
-       name (if  set)  are  retained.  In  a  standalone  negative  assertion,
-       (*ACCEPT)  causes the assertion to fail without any further processing;
+       (*ACCEPT)  in  a  standalone positive assertion causes the assertion to
+       succeed without any further processing; captured strings and a  (*MARK)
+       name  (if  set)  are  retained.  In  a  standalone  negative assertion,
+       (*ACCEPT) causes the assertion to fail without any further  processing;
        captured substrings and any (*MARK) name are discarded.


-       If the assertion is a condition, (*ACCEPT) causes the condition  to  be
-       true  for  a  positive assertion and false for a negative one; captured
+       If  the  assertion is a condition, (*ACCEPT) causes the condition to be
+       true for a positive assertion and false for a  negative  one;  captured
        substrings are retained in both cases.


        The remaining verbs act only when a later failure causes a backtrack to
-       reach  them. This means that their effect is confined to the assertion,
+       reach them. This means that their effect is confined to the  assertion,
        because lookaround assertions are atomic. A backtrack that occurs after
        an assertion is complete does not jump back into the assertion. Note in
-       particular that a (*MARK) name that is  set  in  an  assertion  is  not
+       particular  that  a  (*MARK)  name  that  is set in an assertion is not
        "seen" by an instance of (*SKIP:NAME) latter in the pattern.


-       The  effect of (*THEN) is not allowed to escape beyond an assertion. If
-       there are no more branches to try, (*THEN) causes a positive  assertion
+       The effect of (*THEN) is not allowed to escape beyond an assertion.  If
+       there  are no more branches to try, (*THEN) causes a positive assertion
        to be false, and a negative assertion to be true.


-       The  other  backtracking verbs are not treated specially if they appear
-       in a standalone positive assertion. In a  conditional  positive  asser-
+       The other backtracking verbs are not treated specially if  they  appear
+       in  a  standalone  positive assertion. In a conditional positive asser-
        tion, backtracking (from within the assertion) into (*COMMIT), (*SKIP),
-       or (*PRUNE) causes the condition to be false. However, for both  stand-
+       or  (*PRUNE) causes the condition to be false. However, for both stand-
        alone and conditional negative assertions, backtracking into (*COMMIT),
        (*SKIP), or (*PRUNE) causes the assertion to be true, without consider-
        ing any further alternative branches.
@@ -8996,28 +9015,28 @@


    Backtracking verbs in subroutines


-       These  behaviours  occur whether or not the subpattern is called recur-
+       These behaviours occur whether or not the subpattern is  called  recur-
        sively.


-       (*ACCEPT) in a subpattern called as a subroutine causes the  subroutine
-       match  to succeed without any further processing. Matching then contin-
-       ues after the subroutine call. Perl documents  this  behaviour.  Perl's
+       (*ACCEPT)  in a subpattern called as a subroutine causes the subroutine
+       match to succeed without any further processing. Matching then  contin-
+       ues  after  the  subroutine call. Perl documents this behaviour. Perl's
        treatment of the other verbs in subroutines is different in some cases.


-       (*FAIL)  in  a subpattern called as a subroutine has its normal effect:
+       (*FAIL) in a subpattern called as a subroutine has its  normal  effect:
        it forces an immediate backtrack.


        (*COMMIT), (*SKIP), and (*PRUNE) in a subpattern called as a subroutine
        cause the subroutine match to fail.


-       (*THEN)  skips to the next alternative in the innermost enclosing group
-       within the subpattern that has alternatives. If there is no such  group
+       (*THEN) skips to the next alternative in the innermost enclosing  group
+       within  the subpattern that has alternatives. If there is no such group
        within the subpattern, (*THEN) causes the subroutine match to fail.



SEE ALSO

-       pcre2api(3),    pcre2callout(3),    pcre2matching(3),   pcre2syntax(3),
+       pcre2api(3),   pcre2callout(3),    pcre2matching(3),    pcre2syntax(3),
        pcre2(3).



@@ -9030,7 +9049,7 @@

REVISION

-       Last updated: 27 July 2018
+       Last updated: 28 July 2018
        Copyright (c) 1997-2018 University of Cambridge.
 ------------------------------------------------------------------------------


@@ -10142,7 +10161,14 @@
          (?x)            extended: ignore white space except in classes
          (?xx)           as (?x) but also ignore space and tab in classes
          (?-...)         unset option(s)
+         (?^)            unset imnsx options


+       Unsetting x or xx unsets both. Several options may be set at once,  and
+       a mixture of setting and unsetting such as (?i-x) is allowed, but there
+       may be only one hyphen. Setting (but no unsetting) is allowed after (?^
+       for example (?^in). An option setting may appear at the start of a non-
+       capturing group, for example (?i:...).
+
        The following are recognized only at the very start  of  a  pattern  or
        after  one  of the newline or \R options with similar syntax. More than
        one of them may appear. For the first three, d is a decimal number.
@@ -10311,7 +10337,7 @@


REVISION

-       Last updated: 27 July 2018
+       Last updated: 28 July 2018
        Copyright (c) 1997-2018 University of Cambridge.
 ------------------------------------------------------------------------------



Modified: code/trunk/doc/pcre2pattern.3
===================================================================
--- code/trunk/doc/pcre2pattern.3    2018-07-28 15:08:22 UTC (rev 975)
+++ code/trunk/doc/pcre2pattern.3    2018-07-28 16:23:24 UTC (rev 976)
@@ -1639,19 +1639,24 @@
   xx for PCRE2_EXTENDED_MORE
 .sp
 For example, (?im) sets caseless, multiline matching. It is also possible to
-unset these options by preceding the letter with a hyphen. The two "extended"
-options are not independent; unsetting either one cancels the effects of both
-of them.
+unset these options by preceding the relevant letters with a hyphen, for 
+example (?-im). The two "extended" options are not independent; unsetting either
+one cancels the effects of both of them.
 .P
 A combined setting and unsetting such as (?im-sx), which sets PCRE2_CASELESS
 and PCRE2_MULTILINE while unsetting PCRE2_DOTALL and PCRE2_EXTENDED, is also
-permitted. If a letter appears both before and after the hyphen, the option is
-unset. An empty options setting "(?)" is allowed. Needless to say, it has no
-effect.
+permitted. Only one hyphen may appear in the options string. If a letter
+appears both before and after the hyphen, the option is unset. An empty options
+setting "(?)" is allowed. Needless to say, it has no effect.
 .P
+If the first character following (? is a circumflex, it causes all of the above 
+options to be unset. Thus, (?^) is equivalent to (?-imnsx). Letters may follow 
+the circumflex to cause some options to be re-instated, but a hyphen may not 
+appear.
+.P
 The PCRE2-specific options PCRE2_DUPNAMES and PCRE2_UNGREEDY can be changed in
 the same way as the Perl-compatible options by using the characters J and U
-respectively.
+respectively. However, these are not unset by (?^).
 .P
 When one of these option changes occurs at top level (that is, not inside
 subpattern parentheses), the change applies to the remainder of the pattern


Modified: code/trunk/doc/pcre2syntax.3
===================================================================
--- code/trunk/doc/pcre2syntax.3    2018-07-28 15:08:22 UTC (rev 975)
+++ code/trunk/doc/pcre2syntax.3    2018-07-28 16:23:24 UTC (rev 976)
@@ -1,4 +1,4 @@
-.TH PCRE2SYNTAX 3 "27 July 2018" "PCRE2 10.32"
+.TH PCRE2SYNTAX 3 "28 July 2018" "PCRE2 10.32"
 .SH NAME
 PCRE2 - Perl-compatible regular expressions (revised API)
 .SH "PCRE2 REGULAR EXPRESSION SYNTAX SUMMARY"
@@ -431,7 +431,14 @@
   (?x)            extended: ignore white space except in classes
   (?xx)           as (?x) but also ignore space and tab in classes
   (?-...)         unset option(s)
+  (?^)            unset imnsx options 
 .sp
+Unsetting x or xx unsets both. Several options may be set at once, and a
+mixture of setting and unsetting such as (?i-x) is allowed, but there may be
+only one hyphen. Setting (but no unsetting) is allowed after (?^ for example
+(?^in). An option setting may appear at the start of a non-capturing group, for 
+example (?i:...).
+.P
 The following are recognized only at the very start of a pattern or after one
 of the newline or \eR options with similar syntax. More than one of them may
 appear. For the first three, d is a decimal number.
@@ -612,6 +619,6 @@
 .rs
 .sp
 .nf
-Last updated: 27 July 2018
+Last updated: 28 July 2018
 Copyright (c) 1997-2018 University of Cambridge.
 .fi


Modified: code/trunk/src/pcre2.h.in
===================================================================
--- code/trunk/src/pcre2.h.in    2018-07-28 15:08:22 UTC (rev 975)
+++ code/trunk/src/pcre2.h.in    2018-07-28 16:23:24 UTC (rev 976)
@@ -317,6 +317,7 @@
 #define PCRE2_ERROR_NO_SURROGATES_IN_UTF16         191
 #define PCRE2_ERROR_BAD_LITERAL_OPTIONS            192
 #define PCRE2_ERROR_NOT_SUPPORTED_IN_EBCDIC        193
+#define PCRE2_ERROR_INVALID_HYPHEN_IN_OPTIONS      194



/* "Expected" matching error codes: no match and partial match. */

Modified: code/trunk/src/pcre2_compile.c
===================================================================
--- code/trunk/src/pcre2_compile.c    2018-07-28 15:08:22 UTC (rev 975)
+++ code/trunk/src/pcre2_compile.c    2018-07-28 16:23:24 UTC (rev 976)
@@ -263,7 +263,7 @@
 #define META_SKIP             0x802d0000u  /*         kept        */
 #define META_SKIP_ARG         0x802e0000u  /*           in        */
 #define META_THEN             0x802f0000u  /*             this    */
-#define META_THEN_ARG         0x80300000u  /*               order */  
+#define META_THEN_ARG         0x80300000u  /*               order */


/* These must be kept in groups of adjacent 3 values, and all together. */

@@ -330,7 +330,7 @@
   0,             /* META_ACCEPT */
   0,             /* META_FAIL */
   0,             /* META_COMMIT */
-  1,             /* META_COMMIT_ARG - plus the string length */ 
+  1,             /* META_COMMIT_ARG - plus the string length */
   0,             /* META_PRUNE */
   1,             /* META_PRUNE_ARG - plus the string length */
   0,             /* META_SKIP */
@@ -612,7 +612,7 @@
 /* Verb opcodes, indexed by their META code offset from META_MARK. */


static const uint32_t verbops[] = {
- OP_MARK, OP_ACCEPT, OP_FAIL, OP_COMMIT, OP_COMMIT_ARG, OP_PRUNE,
+ OP_MARK, OP_ACCEPT, OP_FAIL, OP_COMMIT, OP_COMMIT_ARG, OP_PRUNE,
OP_PRUNE_ARG, OP_SKIP, OP_SKIP_ARG, OP_THEN, OP_THEN_ARG };

 /* Offsets from OP_STAR for case-independent and negative repeat opcodes. */
@@ -731,7 +731,7 @@
        ERR61, ERR62, ERR63, ERR64, ERR65, ERR66, ERR67, ERR68, ERR69, ERR70,
        ERR71, ERR72, ERR73, ERR74, ERR75, ERR76, ERR77, ERR78, ERR79, ERR80,
        ERR81, ERR82, ERR83, ERR84, ERR85, ERR86, ERR87, ERR88, ERR89, ERR90,
-       ERR91, ERR92, ERR93 };
+       ERR91, ERR92, ERR93, ERR94 };


 /* This is a table of start-of-pattern options such as (*UTF) and settings such
 as (*LIMIT_MATCH=nnnn) and (*CRLF). For completeness and backward
@@ -1441,41 +1441,41 @@
     escape = -i;                    /* Else return a special escape */
     if (cb != NULL && (escape == ESC_P || escape == ESC_p || escape == ESC_X))
       cb->external_flags |= PCRE2_HASBKPORX;   /* Note \P, \p, or \X */
- 
+
     /* Perl supports \N{name} for character names and \N{U+dddd} for numerical
     Unicode code points, as well as plain \N for "not newline". PCRE does not
-    support \N{name}. However, it does support quantification such as \N{2,3}, 
+    support \N{name}. However, it does support quantification such as \N{2,3},
     so if \N{ is not followed by U+dddd we check for a quantifier. */


     if (escape == ESC_N && ptr < ptrend && *ptr == CHAR_LEFT_CURLY_BRACKET)
       {
       PCRE2_SPTR p = ptr + 1;
-      
-      /* \N{U+ can be handled by the \x{ code. However, this construction is 
-      not valid in EBCDIC environments because it specifies a Unicode 
-      character, not a codepoint in the local code. For example \N{U+0041} 
+
+      /* \N{U+ can be handled by the \x{ code. However, this construction is
+      not valid in EBCDIC environments because it specifies a Unicode
+      character, not a codepoint in the local code. For example \N{U+0041}
       must be "A" in all environments. */
-      
+
       if (ptrend - p > 1 && *p == CHAR_U && p[1] == CHAR_PLUS)
         {
 #ifdef EBCDIC
         *errorcodeptr = ERR93;
-#else        
+#else
         ptr = p + 1;
-        escape = 0;   /* Not a fancy escape after all */ 
+        escape = 0;   /* Not a fancy escape after all */
         goto COME_FROM_NU;
-#endif 
-        }  
-        
-      /* Give an error if what follows is not a quantifier, but don't override 
+#endif
+        }
+
+      /* Give an error if what follows is not a quantifier, but don't override
       an error set by the quantifier reader (e.g. number overflow). */
- 
+
       else
-        { 
+        {
         if (!read_repeat_counts(&p, ptrend, NULL, NULL, errorcodeptr) &&
              *errorcodeptr == 0)
           *errorcodeptr = ERR37;
-        }   
+        }
       }
     }
   }
@@ -1762,9 +1762,9 @@
       {
       if (ptr < ptrend && *ptr == CHAR_LEFT_CURLY_BRACKET)
         {
-#ifndef EBCDIC         
-        COME_FROM_NU: 
-#endif         
+#ifndef EBCDIC
+        COME_FROM_NU:
+#endif
         if (++ptr >= ptrend || *ptr == CHAR_RIGHT_CURLY_BRACKET)
           {
           *errorcodeptr = ERR78;
@@ -2495,15 +2495,15 @@
         goto FAILED;
         }
       *verblengthptr = (uint32_t)verbnamelength;
-      
+
       /* If this name was on a verb such as (*ACCEPT) which does not continue,
-      a (*MARK) was generated for the name. We now add the original verb as the 
-      next item. */  
+      a (*MARK) was generated for the name. We now add the original verb as the
+      next item. */


       if (add_after_mark != 0)
         {
         *parsed_pattern++ = add_after_mark;
-        add_after_mark = 0;   
+        add_after_mark = 0;
         }
       break;


@@ -3498,22 +3498,22 @@
         if (*ptr++ == CHAR_COLON)   /* Skip past : or ) */
           {
           /* Some optional arguments can be treated as a preceding (*MARK) */
- 
+
           if (verbs[i].has_arg < 0)
             {
             add_after_mark = verbs[i].meta;
-            *parsed_pattern++ = META_MARK; 
+            *parsed_pattern++ = META_MARK;
             }
-            
+
           /* The remaining verbs with arguments (except *MARK) need a different
           opcode. */
-          
+
           else
-            {  
+            {
             *parsed_pattern++ = verbs[i].meta +
               ((verbs[i].meta != META_MARK)? 0x00010000u:0);
-            }   
-            
+            }
+
           /* Set up for reading the name in the main loop. */


           verblengthptr = parsed_pattern++;
@@ -3576,17 +3576,37 @@


       else
         {
+        BOOL hyphenok = TRUE;
         top_nest->reset_group = 0;
         top_nest->max_group = 0;
         set = unset = 0;
         optset = &set;


+        /* ^ at the start unsets imnsx and disables the subsequent use of - */
+
+        if (ptr < ptrend && *ptr == CHAR_CIRCUMFLEX_ACCENT)
+          {
+          options &= ~(PCRE2_CASELESS|PCRE2_MULTILINE|PCRE2_NO_AUTO_CAPTURE|
+                       PCRE2_DOTALL|PCRE2_EXTENDED|PCRE2_EXTENDED_MORE);
+          hyphenok = FALSE;
+          ptr++; 
+          }
+
         while (ptr < ptrend && *ptr != CHAR_RIGHT_PARENTHESIS &&
                                *ptr != CHAR_COLON)
           {
           switch (*ptr++)
             {
-            case CHAR_MINUS: optset = &unset; break;
+            case CHAR_MINUS:
+            if (!hyphenok)
+              {
+              errorcode = ERR94;
+              ptr--;  /* Correct the offset */
+              goto FAILED;
+              }
+            optset = &unset;
+            hyphenok = FALSE; 
+            break;


             case CHAR_J:  /* Record that it changed in the external options */
             *optset |= PCRE2_DUPNAMES;
@@ -3644,9 +3664,10 @@
           }
         else *parsed_pattern++ = META_NOCAPTURE;


-        /* If nothing changed, no need to record. */
+        /* If nothing changed, no need to record. The check of hyphenok catches 
+        the (?^) case. */


-        if (set != 0 || unset != 0)
+        if (set != 0 || unset != 0 || !hyphenok)
           {
           *parsed_pattern++ = META_OPTIONS;
           *parsed_pattern++ = options;
@@ -3952,7 +3973,7 @@
           {
           if (++ptr >= ptrend || !IS_DIGIT(*ptr)) goto BAD_VERSION_CONDITION;
           minor = (*ptr++ - CHAR_0) * 10;
-          if (IS_DIGIT(*ptr)) minor += *ptr++ - CHAR_0; 
+          if (IS_DIGIT(*ptr)) minor += *ptr++ - CHAR_0;
           if (ptr >= ptrend || *ptr != CHAR_RIGHT_PARENTHESIS)
             goto BAD_VERSION_CONDITION;
           }
@@ -5709,7 +5730,7 @@
     cb->had_pruneorskip = TRUE;
     /* Fall through */
     case META_MARK:
-    case META_COMMIT_ARG: 
+    case META_COMMIT_ARG:
     VERB_ARG:
     *code++ = verbops[(meta - META_MARK) >> 16];
     /* The length is in characters. */
@@ -8058,7 +8079,7 @@
       break;


       case OP_MARK:
-      case OP_COMMIT_ARG: 
+      case OP_COMMIT_ARG:
       case OP_PRUNE_ARG:
       case OP_SKIP_ARG:
       case OP_THEN_ARG:
@@ -8367,7 +8388,7 @@
     break;


     case META_MARK:     /* Add the length of the name. */
-    case META_COMMIT_ARG: 
+    case META_COMMIT_ARG:
     case META_PRUNE_ARG:
     case META_SKIP_ARG:
     case META_THEN_ARG:
@@ -8558,7 +8579,7 @@
     goto EXIT;


     case META_MARK:
-    case META_COMMIT_ARG: 
+    case META_COMMIT_ARG:
     case META_PRUNE_ARG:
     case META_SKIP_ARG:
     case META_THEN_ARG:
@@ -8630,31 +8651,31 @@
     case META_LOOKAHEADNOT:
     pptr = parsed_skip(pptr + 1, PSKIP_KET);
     if (pptr == NULL) goto PARSED_SKIP_FAILED;
-    
+
     /* Also ignore any qualifiers that follow a lookahead assertion. */
-    
+
     switch (pptr[1])
       {
       case META_ASTERISK:
       case META_ASTERISK_PLUS:
-      case META_ASTERISK_QUERY:   
+      case META_ASTERISK_QUERY:
       case META_PLUS:
-      case META_PLUS_PLUS: 
+      case META_PLUS_PLUS:
       case META_PLUS_QUERY:
       case META_QUERY:
       case META_QUERY_PLUS:
-      case META_QUERY_QUERY:       
+      case META_QUERY_QUERY:
       pptr++;
       break;
-      
+
       case META_MINMAX:
       case META_MINMAX_PLUS:
       case META_MINMAX_QUERY:
       pptr += 3;
       break;
-      
+
       default:
-      break;      
+      break;
       }
     break;


@@ -9026,7 +9047,7 @@
     break;


     case META_MARK:
-    case META_COMMIT_ARG: 
+    case META_COMMIT_ARG:
     case META_PRUNE_ARG:
     case META_SKIP_ARG:
     case META_THEN_ARG:


Modified: code/trunk/src/pcre2_error.c
===================================================================
--- code/trunk/src/pcre2_error.c    2018-07-28 15:08:22 UTC (rev 975)
+++ code/trunk/src/pcre2_error.c    2018-07-28 16:23:24 UTC (rev 976)
@@ -179,7 +179,8 @@
   "internal error: bad code value in parsed_skip()\0"
   "PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES is not allowed in UTF-16 mode\0"
   "invalid option bits with PCRE2_LITERAL\0"
-  "\\N{U+dddd} is not supported in EBCDIC mode\0" 
+  "\\N{U+dddd} is not supported in EBCDIC mode\0"
+  "invalid hyphen in option setting\0"
   ;


/* Match-time and UTF error texts are in the same format. */

Modified: code/trunk/testdata/testinput1
===================================================================
--- code/trunk/testdata/testinput1    2018-07-28 15:08:22 UTC (rev 975)
+++ code/trunk/testdata/testinput1    2018-07-28 16:23:24 UTC (rev 976)
@@ -6252,4 +6252,10 @@


/(*COMMIT:]w)/

+/(?i)A(?^)B(?^x:C D)(?^i)e f/
+    aBCDE F
+\= Expect no match
+    aBCDEF
+    AbCDe f
+    
 # End of testinput1 


Modified: code/trunk/testdata/testinput2
===================================================================
--- code/trunk/testdata/testinput2    2018-07-28 15:08:22 UTC (rev 975)
+++ code/trunk/testdata/testinput2    2018-07-28 16:23:24 UTC (rev 976)
@@ -5453,4 +5453,10 @@
 \= Expect no match
     axy


+/(?^x-i)AB/
+
+/(?^-i)AB/
+
+/(?x-i-i)/
+
# End of testinput2

Modified: code/trunk/testdata/testoutput1
===================================================================
--- code/trunk/testdata/testoutput1    2018-07-28 15:08:22 UTC (rev 975)
+++ code/trunk/testdata/testoutput1    2018-07-28 16:23:24 UTC (rev 976)
@@ -9912,4 +9912,13 @@


/(*COMMIT:]w)/

+/(?i)A(?^)B(?^x:C D)(?^i)e f/
+    aBCDE F
+ 0: aBCDE F
+\= Expect no match
+    aBCDEF
+No match
+    AbCDe f
+No match
+    
 # End of testinput1 


Modified: code/trunk/testdata/testoutput2
===================================================================
--- code/trunk/testdata/testoutput2    2018-07-28 15:08:22 UTC (rev 975)
+++ code/trunk/testdata/testoutput2    2018-07-28 16:23:24 UTC (rev 976)
@@ -16622,6 +16622,15 @@
     axy
 No match, mark = X


+/(?^x-i)AB/
+Failed: error 194 at offset 4: invalid hyphen in option setting
+
+/(?^-i)AB/
+Failed: error 194 at offset 3: invalid hyphen in option setting
+
+/(?x-i-i)/
+Failed: error 194 at offset 5: invalid hyphen in option setting
+
# End of testinput2
Error -70: PCRE2_ERROR_BADDATA (unknown error number)
Error -62: bad serialized data