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

    Specifies that only those history entries dated on or after the
    given time are to be displayed. The time value can be an absolute,
    delta, or combination time value, or one of the following
    keywords: TODAY, TOMORROW, or YESTERDAY. When the /SINCE qualifier
    is omitted, all transactions that occurred since the library was
    created are displayed. If you specify the /SINCE qualifier but do
    not specify a value, CMS defaults to /SINCE=TODAY.