Yeah, I wouldn't mind about @ either, besides it's a character known from DOS/batch scripting. I just suggested ! because it's already used as a special character in two cases (/if statements and escaping evaluation). I don't know how confusing this can be but I've never heard anybody complaining about the two different applications of ! currently. Besides, I would expect people who would use the "!$identifier" expression for the purpose of a /noop to be quite familiar with scripting, so as to not confuse this with "$!identifier". I'm not definitely in favour or against a specific char but, generally, the fewer special characters and 'exceptions' to rules the better.
