H'm. I can't seem to find any reference to tr///u in the docs for 5.8.4? It gives a syntax error when I use it with perl -e.

%tied_array and @tied_hash seem to have backwards sigils.

Very good idea, though. I've been looking for something that tells me which features were introduced when so I can know which version of perl my program requires rather than just sort of blindly guessing or requiring whatever I have (which is often not necessary).