p When matching preserve a copy of the matched string so
that ${^PREMATCH}, ${^MATCH}, ${^POSTMATCH} will be
defined (ignored starting in v5.20) as these are always
- defined starting in that relese
+ defined starting in that release
o Compile pattern only once.
a ASCII-restrict: Use ASCII for \d, \s, \w; specifying two
a's further restricts things to that that no ASCII