Ah, so unpack "U" will pull a multibyte character, ignoring the char/byte orientation on the string being scanned. That makes sense. I was thinking unpack using C and pack using U, or something along those lines, but could not see how unpack/pack could work.

In current Perl, I think the taint-like trick is faster than having to pull and repack all the chars in the string.

I look forward to the new features when v5.8 comes out. Thanks for pointing that out. It's very annoying that there's not a set and test function for the mode bit, especially in the even earlier days when not all the built-ins worked right yet. Even today without input disciplines, we need to set the charmode on everything read in from a file!