SESSIONC →     RPL:     ACB field → ACB
                        Note: ARG and NIB are mutually exclusive.
                        ARG field = CID of session or pending active session
                        NIB field → NIB: (only to send negative response
                             to BIND)
                             Note: NAME and CID
                             are mutually exclusive.
                             NAME is required if
                             the NIB field is used.
                             NAME field = symbolic name of PLU
                             NETID field = symbolic network identifier of PLU
                             CID field = CID of pending active session
                             LISTEND field = YES
                        Note: ECB and EXIT are mutually exclusive.
                        If ECB is used, only one is allowed.
                        ECB field → external ECB
                        ECB field = internal ECB
                        EXIT field → RPL exit routine
                        BRANCH field = YES|NO
                        STYPE field = REQ|RESP

 
                        If RESPONSE = NEX and CONTROL = STSN,
                        IBSQVAL field = inbound sequence
                             number
                        IBSQAC field = RESET|TSTPOS|
                             INVALID|TESTNEG
                        OBSQVAL field = outbound sequence
                             number
                        OBSQAC field = RESET|TESTPOS|
                             INVALID|TESTNEG