Applies only to X25 circuits.  Defines the usage type of an X25
 virtual circuit.  The possible values are:

     INCOMING        Applies only to X25 DLM SVCs.
                     The  circuit  is used only for
                     incoming calls.

     OUTGOING        Applies only to X25 DLM SVCs.
                     The  circuit  is used only for
                     outgoing calls.

     PERMANENT       This  parameter  is  mandatory
                     for X25 PVCs.  The circuit is
                     permanently connected to a remote
                     DTE, and does not need to be
                     switched dynamically.