On Wed, Dec 12, 2007 at 04:13:03PM +0000, Philip Hazel wrote: > The second can't - it hasn't matched the parentheses, so how can it back
> reference them? Forward backreferences make sense only inside loops,
> when the parentheses have matched on a previous iteration of the loop.
>
> Note: a backreference is *not* a "subroutine call". PCRE (and Perl 5.10)
> do have "subroutine calls". Try
>
> /^abc(?1)(d)/
>
> Grep for "subroutine" in 'man pcrepattern'.
ahh, that was helpful. Many thanks for your clarification.
