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

       /BEFORE[=time]

    Selects only those files dated prior to the specified time. You
    can specify time as absolute time, as a combination of absolute
    and delta times, or as one of the following keywords: BOOT,
    LOGIN, TODAY (default), TOMORROW, or YESTERDAY. Specify one of
    the following qualifiers with the /BEFORE qualifier to indicate
    the time attribute to be used as the basis for selection:
    /BACKUP, /CREATED (default), /EXPIRED, or /MODIFIED.

    For complete information on specifying time values, refer to the
    OpenVMS User's Manual or the online help topic DCL_Tips (subtopic
    Date_Time).