Selective receiver ERP sense codes supported

During output, IMS recognizes receipt of the SNA-defined selective receiver ERP system sense code when assuming either half-session role, returns the message to the queue, ensures that a synchronizing event occurs to end the other half session's ERP purge cycle, and enters a receive state that can be satisfied only by input (ERP message) from the other half session.

When receiving this ERP message, IMS takes one of three actions based on the FMH7 sense code and the DFC protocols associated with the received ERP message:
  • The ERP message (DFS2083) is routed to the IMS master terminal operator as a warning that an error condition was recovered on the ISC session. The ISC output message in error is either dequeued or retransmitted, and normal input or output operations continue. The message is retransmitted when an FMH7 is received with sense code X'0866' and without EB. The message is dequeued when an FMH7 is received with EB during test, response, or conversational mode output.
  • The ERP message (DFS2073) is routed to the IMS LTERM associated with the IMS terminal operator who was the source (using an IMS message switch) of the ISC message switch output in error. The ISC output message in error is dequeued and normal input or output operations continue.
  • The ERP message (DFS2073) is routed to the IMS master terminal operator and the ISC session is terminated. The ISC output message in error remains on the IMS message queue.

    However, if ERPKPSES=Y and the sender ERP sense code is X'08460000', the original message is dequeued and the session remains active. In this case, which terminal the ERP message (DFS2073I) is passed to depends on the specification of the COMPTn parameter and which side initiated the message in error. If the original message is initiated from the secondary side of the session and COMPTn=SINGLE2 | MULT1 | MULT2, the ERP message is routed to the original inputting terminal. Otherwise, the ERP message is routed to the MTO.

All ERP messages must carry an EB or CD or the session is terminated. Further, EB received with the ERP message forces end of IMS conversation, response, or test mode. When conversation mode is terminated, the Conversation Abnormal Termination exit routine is also invoked as would occur when an IMS /EXIT command is received. IMS processes FMH7 ERP messages received based on the FMH7 sense code and the DFC protocols associated with the message as in these subtopics.