Use the LOOP CIRCUIT command to test a specified circuit in the
 network.  This command does not apply to X25 circuits.  The
 parameters are optional and can be entered in any order.

 LOOP   CIRCUIT circuit-id   ASSISTANT PHYSICAL ADDRESS address
                             ASSISTANT NODE node-id
                             COUNT number
                             HELP help-type
                             LENGTH number
                             NODE node-id
                             PHYSICAL ADDRESS address
                             WITH
                               MIXED
                               ONES
                               ZEROES

 All underscores found in parameters must be replaced with spaces
 when parameters are used in NCP commands.