It's been indicated that several regex modifiers that are found in Perl5 are gone. That's all well and good, unless you're using the Perl5 modifier to port code to perl6. What happens if you're trying to port in a regex that made use of one of the now-obsolete modifiers? Bear in mind that there are new s and x modifiers that have nothing to do with their perl5 homonyms.
Suggestion: let the Perl5 modifier take an optional argument that consists of perl5-compatable, perl6-incompatable modifiers: m, s, and/or x. The other regex-related perl5-compatable modifiers (e, g, and o) have more to do with the match and substitute functions than with the patterns themselves, and so can be updated to perl6 standards without regard to the pattern used. -- Jonathan "Dataweaver" Lang