VMS Help MMS, Qualifiers, /RULES  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    /RULES[=filespec] (D)
    /NORULES

    Controls whether MMS applies user-defined built-in rules and
    a suffixes-precedence list when it builds a system. These
    qualifiers affect the behavior of MMS, but not the execution
    of action lines.

    The filespec is an OpenVMS file specification or a logical
    name that identifies the file of user-created rules that MMS
    is to use. When you supply a file specification with the /RULES
    qualifier, MMS replaces the built-in rules it normally uses with
    the built-in rules and suffixes list in the file you specify.
    The file specified with /RULES has precedence over the file
    represented by MMS$RULES.

    If you specify /RULES without a file specification, MMS
    translates the logical name MMS$RULES to locate the user-defined
    built-in rules file. If MMS$RULES is not defined, MMS uses its
    own built-in rules.

    The /NORULES qualifier prevents MMS from using its built-in
    rules or the suffixes-precedence list. It also prevents MMS from
    applying user-defined rules and default macros. When you specify
    /NORULES, MMS applies only the dependency rules contained in the
    description file.