If it's a comment in assembler then it has to be preceeded by ;.

MCS is just an editor. Depending on which assembler you're using, PM or
MPASMWIN, all error codes will be found in that assemblers help file.

For PM look in PM.TXT. For MPASMWIN look in the MPASM help file. The only
errors (that I know of) MCS will pass back are errors generated by the
assembler you're using.