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

       /SUPERVISOR_MODE (default)

    Creates a supervisor-mode device and assigns the logical name
    DECW$DISPLAY to point to it. This qualifier must be used with the
    /CREATE qualifier. When the user logs out, the device is deleted.