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

    Default: False             Value: True or false

    Indicates whether the Test Mode signal is to be monitored. Use the
    value false if the DCE deals with the Test Mode signal.

    Setting this characteristic to true means that the interchange
    circuit status attribute test mode will also be displayed as
    Unknown.