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

       /OPERATOR=string

    Specifies a message string of up to 255 characters to be sent to
    the operator just before the print job begins to print. Enclose
    the message in quotation marks (" ")  if it contains spaces,
    special characters, or lowercase characters.