/usr/src/perl/pod/perlfaq6/How_can_I_match_a_locale_smart_v.pod

How can I match a locale-smart version of /[a-zA-Z]/?

One alphabetic character would be /[^\W\d_]/, no matter what locale you're in. Non-alphabetics would be /[\W\d_]/ (assuming you don't consider an underscore a letter).