Irrecoverable-inquiry transactions

IMS treats an irrecoverable transaction in the same manner as a recoverable transaction, except that all processing required to achieve recoverability is eliminated. As a result, irrecoverable transactions require less processing time but can be lost in the event of a failure (for example, line failure, processor failure, queue failure) in the network.

An irrecoverable transaction need not request a DR1 or DR2. Because recoverability is not guaranteed, the receiver of the message is not required to acknowledge receipt. An irrecoverable transaction should, however, request an exception DR1 or DR2. The exception DR1 or DR2 requires fewer line transmissions than DR1 or DR2, because under normal circumstances no response is returned.