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

    /CHECK_STATUS
    /NOCHECK_STATUS (D)

    Controls whether MMS returns a value in the symbol MMS$STATUS
    instead of updating a target. This symbol contains the status
    of the last action line executed by MMS. These qualifiers affect
    both the execution of action lines and the behavior of MMS.

    When you specify the /CHECK_STATUS qualifier, MMS checks whether
    a target is up-to-date by determining whether any actions would
    be executed if the /ACTION qualifier was specified. MMS issues
    an informational message and sets MMS$STATUS to 1 if no actions
    would be executed (that is, if the target is up-to-date). If the
    target needs to be updated, MMS sets the MMS$STATUS value to 0.

    /CHECK_STATUS has precedence over both the /ACTION and "/REVISE_
    DATE" qualifiers if they appear on the same command line. In this
    case, only /CHECK_STATUS is processed.

    The /NOCHECK_STATUS qualifier directs MMS to process the
    description file as it normally would, executing action lines
    if necessary.