/SINCE="time-spec"
       /BEFORE="time-spec"

    Sets the lower and/or higher limits on the collection times of
    the SPM data being merged. These optional qualifiers can only be
    specified together with the /SPM_PROCESS_ID qualifier. The time-
    spec parameters must be enclosed within double quotation marks ("
    ") and must be valid OpenVMS absolute date/time specifications,
    as described in the DCL Concepts manual.