Sender-detected errors on nonpaged messages

When an error is detected after initiating transmission of a single SNA nonpaged, multi-RU message, the sender can send the SNA unsolicited CANCEL command.

IMS sends unsolicited CANCEL only if a current output message is terminated by an operator /DEQUEUE command entered prior to the last segment of the message (single SNA chain) being transmitted.

If IMS receives an unsolicited CANCEL while data is being received by IMS, the message is discarded or backed out.