/sys$common/syshlp/helplib.hlb MMS, Generating Description Files, Qualifiers, /CMS  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    /CMS
    /NOCMS (D)

    Controls whether MMS looks for source files and include files in
    the current default CMS library. CMS must be installed on your
    system. If a directory-spec is associated with a file, that is the
    directory into which MMS fetches the file when building the target.