Huh, PCRE is universal (almost, not in e.g. Emacs :-( ) and supports (almost) everything?

Edit: Cough, after rechecking... PCRE is not as universal as I thought. It seems I've been lucky. :-) http://en.wikipedia.org/wiki/Comparison_of_regular_expressio...

Edit 2: "Atomic groups" on that wikipedia link is when you can write a full grammar in a large regexp, right? Answer myself: No, it is the name for stopping backtracking. I've seen it as named "possessive" (perldoc perlre).