Library /sys$common/syshlp/ncphelp.hlb SET, CIRCUIT, USAGE  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 Usage-type Applies only to X.25 circuits.  Specifies the usage
 type of an X.25 virtual circuit.  The possible values usage-types
 are:

 INCOMING   Applies only to X.25 DLM SVCs.  The circuit is used
            only for incoming calls.

 OUTGOING   Applies only to X.25 DLM SVCs.  The circuit is used
            only for outgoing calls.

 PERMANENT  This parameter is mandatory for X.25 PVCs.
            The circuit is permanently connected to a remote
            DTE, and does not need to be switched dynamically.