Re: [FYI] use encoding 'non-utf8-encoding'; use CGI;

However, I will need to stare at your example some more, since
for simpler cases I think tr/// *is* obeying the 'use encoding':

use encoding 'greek';
($a = "\x{3af}bc\x{3af}de") =~ tr/\xdf/a/;
print $a, "\n";

This does print "abcade\n", and it also works when I replace the \xdf
with the literal \xdf.

-- 
Jarkko Hietaniemi <jhi(_at_)iki(_dot_)fi> http://www.iki.fi/jhi/ "There is this 
special
biologist word we use for 'stable'.  It is 'dead'." -- Jack Cohen