Does it have to be a regexp? No spoilers, since it's not what was asked for, but this is *somewhat* simpler: (1) !(tr/a/a/ % 2) (2) tr/b/b/ % 2 (3) (tr/b/b/ % 2) & !(tr/a/a/ % 2) -- Peter Scott Pacific Systems Design Technologies ==== Want to unsubscribe from Fun With Perl? Well, if you insist... ==== Send email to <fwp-request@technofile.org> with message _body_ ==== unsubscribe