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

    /OVERRIDE
    /NOOVERRIDE (D)

    Controls the order in which MMS applies definitions when it
    processes macros. These qualifiers affect the behavior of MMS,
    but not the execution of action lines.

    When you specify the /OVERRIDE qualifier, MMS overrides the macro
    definitions in the description file with CLI symbol definitions.
    To find the macro definitions that should have precedence,
    MMS looks at symbols defined by the CLI assignment statement,
    scanning the CLI symbol table for the body of the macro. If the
    body of the macro is not in the CLI symbol table, MMS substitutes
    a null string for all invocations of the macro.

    The /OVERRIDE qualifier imposes the following order of
    application when MMS processes macro definitions:

    1. Command line

    2. CLI symbol

    3. Description file

    4. Built-in

    Once MMS finds a definition for a macro, it does not search those
    locations farther down the list for more definitions. If MMS
    finds more than one definition in the same location (such as on a
    command line), it uses the last definition it processed, unless
    the location is a description file. MMS issues an error message
    if a macro is defined more than once in a description file.

    The /NOOVERRIDE qualifier imposes the following order, which is
    the default hierarchy:

    1. Command-line

    2. Description file

    3. Built-in

    4. CLI symbol