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

    Lists current reservations that were executed prior to the
    specified time. The date value can be an absolute, delta, or
    combination time value, or one of the following keywords: TODAY,
    TOMORROW, or YESTERDAY. By default, CMS displays all existing
    reservations.