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

1 - /DEFAULT

       /DEFAULT

    Overrides any previous SET DAY specification and specifies that
    the normal UAF defaults are to be used to determine today's day
    type.

2 - /LOG

       /LOG
       /NOLOG (default)

    Controls whether log information is displayed at the terminal to
    confirm that the new SET DAY information has been set.

3 - /PRIMARY

       /PRIMARY

    Sets today until midnight to a primary day.

4 - /SECONDARY

       /SECONDARY

    Sets today until midnight to a secondary day.