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

   /SINCE=time

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