in reply to Unicode, regex's, encodings, and all that (Perl 5.6 and 5.8)

is use utf8 necessary for extended variable names?

Yes, if utf8 names are used in perl source, you must use utf8;. I gave an example of a utf8 named sub in [5.8.0 Note] A Sub Named Sigma. That code failed without the pragmatic. I wish I could answer the rest of your questions as easily.

After Compline,
Zaxo

In Section Seekers of Perl Wisdom