Library /sys$common/syshlp/ncphelp.hlb LOOP, CIRCUIT, ASSISTANT PHYSICAL ADDRESS p-address  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 Applies only to broadcast circuits.  Identifies the physical  address
 of the node that will perform the role of loopback  assistant for
 third-party loop testing.  The address cannot be a multicast address.
 If the HELP parameter is specified, you must specify either the
 ASSISTANT NODE parameter or the ASSISTANT PHYSICAL ADDRESS parameter.