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

       /PROTOCOL=DDCMP
       /PROTOCOL=NONE (default)

    On VAX, controls whether the terminal port specified is changed
    into an asynchronous DDCMP line. The /PROTOCOL=NONE qualifier
    changes an asynchronous DDCMP line back into a terminal line.
    Note that /PROTOCOL=DDCMP is a permanent characteristic;
    therefore, the /PERMANENT qualifier is not required.