/COMMENTS

    /COMMENTS={AS_IS | SPACE}
    /COMMENTS=SPACE (D) (ANSI89, RELAXED, and MIA compiler modes)
    /NOCOMMENTS (D) (all other compiler modes)

 Governs whether or not comments appear in preprocess output files
 and, if they are to appear, whether they appear themselves or are
 replaced by a single space.  Specify one of the following qualifier
 options:

  AS_IS     Specifies that the comment appears in the output file.

  SPACE     Specifies that a single space replaces the comment in
            the output file.

NOCOMMENTS specifies that nothing replaces the comment in the output
file.  This can result in inadvertent token pasting.

The VSI C preprocessor might replace a comment at the end of a line
or on a line by itself with nothing, even if /COMMENTS=SPACE is
specified.  Doing so does not change the meaning of the program.

The default is /COMMENTS=SPACE for the ANSI89, RELAXED, and MIA
compiler modes.  The default is /NOCOMMENTS for all other compiler
modes.

Specifying just /COMMENTS defaults to /COMMENTS=AS_IS.