Library /sys$common/syshlp/nclhelp.hlb set, x25_protocol, dte, maximum_throughput_class  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Default: 4800          Value: See description

    Maximum value for the throughput class (65535) of any virtual
    circuit on the DTE. The value specified must be one of the
    following: 0, 75, 150, 300, 600, 1200, 2400, 4800, 9600, 48000,
    or 64000. The value must be greater than or equal to the value of
    the minimum throughput class characteristic.