Selective receiver ERP

Selective receiver error recovery procedure (ERP) is initiated using the X'08460000' sender ERP sense code.

The procedure has these characteristics:
  • The procedure is symmetrical to both half sessions.
  • ERP messages can be sent by the sender of the exception response indicating selective receiver ERP. An ERP message is an ERP FMH7 header followed by an IMS error message. Each selective receiver ERP message is preceded by an ERP FMH7 function management header.
  • Contention for ERP messages does not occur for the exception response sender.
  • ERP messages can consist of a full chain of arbitrary length, but must immediately follow the exception response indicating selective receiver ERP.
  • The ERP message is recognized by the receiver for special processing.
  • The response sender has an opportunity to reset the function management level bracket and send/receive states.

The ERP messages sent by IMS have associated default IMS message output descriptors (MODs) and display output formats (DOFs). The error message is formatted using SNA character string (SCS) controls even when sent to a component defined with MFS.

If necessary, the sender of the exception response enters into an ERP PURGE mode until both half sessions' send/receive states are again synchronized. The receiver of the exception response must cause the resynchronizing event.