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

    Sets the device type when the /INQUIRE qualifier is specified
    and the DEC_CRT characteristic is set. The SET TERMINAL command
    reads the current screen size from the terminal and sets the
    corresponding page length and page width values appropriately.
    The default device type is UNKNOWN. Works only on DIGITAL
    terminals, and not on LA36 or VT05 terminals. Some VT100 family
    terminals, including the VT101 and VT105, return a VT100 type
    response. LA38 terminals respond as LA43 terminals.

                                   NOTE

       The SET TERMINAL/INQUIRE command works correctly on DIGITAL
       supplied VT100 and later terminals. Some personal computer
       terminal emulators may not work correctly, because they do
       not correctly emulate all VT100 escape sequences. Compaq
       recommends that users who experience problems with these
       terminal emulators contact the terminal emulator supplier.

    You can include the SET TERMINAL/INQUIRE command in your
    LOGIN.COM file to detect the terminal type automatically.

    If you specify /INQUIRE=OLD, OpenVMS sets the terminal window
    to 24 lines by 80 columns and ignores the real terminal size.
    (This is the behavior of the SET TERMINAL/INQUIRE command prior
    to OpenVMS Version 6.2.)

                                 CAUTION

       This qualifier clears the type-ahead buffer. If the response
       sequence is unrecognized, no action message or error message
       is displayed. The /INQUIRE qualifier should be used only on
       DIGITAL terminals; however, the LA36 and VT05 terminals do
       not support this feature.