MASM naming convention for identifiers beginning with a question mark?

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) ?

Solution

I'm not aware of any documented convention for leading ?s. But MASM appears to use two leading question marks when expanding macros that contain LOCAL labels.

This isn't clearly documented as a convention AFAIK, but the MASM Programmer's Guide kind of mentions it in passing in the section named "Defining Local Symbols in Macros".

We can also test this ourselves by writing a simple piece of code:

.686
.model flat,stdcall
option casemap:none

FOO MACRO
LOCAL local_to_foo
local_to_foo:
ENDM

.code

start:

FOO
FOO

END start

If we tell MASM to generate a listing file for this (with the /Fl option), the listing for the code section will look like this:

 00000000           .code

 00000000           start:

                FOO
 00000000            1  ??0000:
                FOO
 00000000            1  ??0001:

                END start

Bottom line is, it's probably best for you as a programmer to not use leading question marks in your identifiers, just like the MASM Programmer's Guide advises you not not use leading @ characters since MASM uses that for some predefined special symbols.