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

       /COMMSYNC
       /NOCOMMSYNC (default)

    Allows connection of asynchronous printers and other devices
    to terminal ports, using standard modem control signals as flow
    control. Transmission to the device stops if either data set
    ready (DSR) or clear to send (CTS) EIA modem control signals are
    dropped. Transmission resumes when both signals are present.

    The /COMMSYNC qualifier and the /MODEM qualifier are mutually
    exclusive.

    The COMMSYNC feature has the following limitations:

    o  Cannot be used on LAT ports

    o  Can only be used on ports with full modem control

    o  Should not be used in conjunction with Xon/Xoff flow control
       (the port may hang)

                                 CAUTION

       The /COMMSYNC qualifier should never be set on a line with
       a modem that is intended for interactive use. The qualifier
       disables the modem terminal characteristic that disconnects
       a user process from the terminal line in case of a modem
       phone line failure. With the /COMMSYNC qualifier enabled,
       the next call on the terminal line could be attached to the
       previous user's process. Security administrators should
       be aware that the characteristic should not be used on
       interactive terminal ports. In addition, the /COMMSYNC
       qualifier is not supported on a port connected to a LAT
       line.