Looking at the BNF grammar for MASM, an identifier can be named as follows:
The first character of the identifier can be an upper or lower-case alphabetic character ([A–Za-z]) or any of these four characters: @ _ $ ? The remaining characters can be any of those same characters or a decimal digit ([0–9]). Maximum length is 247 characters.
Are there any MASM (or assembly) naming conventions for beginning an identifier with a ? (question mark) ?