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

       /OPERATION=(keyword[,...])

    Specifies one or more of the following operations as the value
    for keyword:

       INSTALL
       RECONFIGURE
       REGISTER_PRODUCT
       REGISTER_VOLUME
       REMOVE

    Parentheses (())  are optional only when you specify a single
    keyword. They are required when you specify multiple keywords.