Library /sys$common/syshlp/nclhelp.hlb set, modem_connect, line, speed  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Default: 0

    High speed (in bits per second) to be used on the line. This value
    is always used on asynchronous links. It is used on synchronous
    links only in the following circumstances:

    o  When the value of the clock characteristic is internal

    o  When a null modem cable is detected

    o  When using a loopback mode that uses internal clocking

    You can modify this characteristic only when the entity is
    disabled.