YAPE::Regex::Explain states that it handles regular expressions up to Perl 5.6. I am doing some work involving Postgres, which uses Posix regexes. I have found documentation indicating that all Posix character classes are in the current Perl version. I have been struggling to find anything indicating whether this has always been the case and what the position is with other aspects of regexes. It would be ideal if Perl 5.6 were a superset of Posix. It would be good if I knew which Posix features Perl 5.6 did not support and when or if support was added to Perl. Can anyone lighten my darkness, please?