VMS Help CMS, SHOW, GENERATION, Qualifiers, /BEFORE=date-time  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Displays all of the generation information before a specified time.

    The time value can be an absolute, delta, or combination time
    value, or one of the following keywords: TODAY, TOMORROW, or
    YESTERDAY.  If the time value is a future value, CMS uses the
    current time.  If no time value is supplied, CMS used TODAY.