Simple support for Perl-like syntax in GNU Regex:

If Regex is compiled with PERLSYNTAX #defined, then the following
operators can be used in a regexp:

     \s	 -- matches whitespace
     \S  -- matches non-whitespace
     \w  -- matches alphanumeric (+ '_')
     \W  -- matches non-alphanumeric
     \d  -- matches numeric
     \D  -- matches non-numeric char.
     \A  -- is equal to beginning-of-buffer operator
     \Z  -- is the same as end-of-buffer operator
	     
Also defined these

     \n  -- matches newline
     \f  -- matches formfeed
     \r  -- matches carriage return
     \t  -- matches (horisontal) tab
     \v  -- matches a vertical tab
     \a  -- matches the alarm bell
     \e  -- matches escape (\033)


Perl5 regexp features not supported
===================================

* At the moment there is no support for non-greedifying operators such as * by
  appending a ?, i.e. (pat)*? will not match pat a minimal number of times,
  * guzzles as many chars as possible.

* Not possible to quote hex(\xhh) or octal(\ooo) values.

* No support for \l \L \u \U to force matching of lower or upper case patterns
  until a \E is seen. (Same goes for \Q to quote metachars.)

* None of the regexp extension mechanisms of Perl5  (?...) is supported.
  See perlre for details of what you are missing out on.