your exact problem still isn't clear to me, but certainly there've been times when I want to search for some array of characters in a binary blob. i don't believe i've needed anything beyond a literal string of bytes, but i could imagine from there the utility of something regexp-like.
i think the answer is just "no, there's no way to do that today". and i'd strongly advise keeping that tool as far away from any discussion of localization or character sets or runes or the like. there's oughtn't be any mode switching or the like: it's utf-8 encoded unicode runes, or it's binary, not characters at all. hex editors are useful sometimes. being able to do more complicated searches/edits/replaces/whatever could be similarly useful sometimes. but don't go anywhere near the character set or localization discussions with it. anthony
