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

       /SET_SPEED
       /NOSET_SPEED

    Requires either LOG_IO (logical I/O) or PHY_IO (physical I/O)
    privilege.

    Controls whether the /SPEED qualifier can be used to change the
    terminal speed.