"For compatibility with Perl, \s does not match the VT character (code
11). This makes it different from the the POSIX "space" class. The \s
characters are HT (9), LF (10), FF (12), CR (13), and space (32). If
"use locale;" is included in a Perl script, \s may match the VT
character. In PCRE, it never does. "