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

    Used with the /INCLUDE or /EXCLUDE qualifier, specifies that the
    node names provided are to be added to the previously established
    include or exclude lists.

    Used with the /RESERVE qualifier, specifies that the user
    names provided are to be added to the previously established
    reservation lists.

    When you use /ADD, you do not need to retype the entire list to
    add a new node name or user name.