The sender optionally can specify eight bytes of user data to be associated with the message-out request with the IXCMSGOX USERDATA parameter. When the message completes, the system passes a copy of this user data in the MNPL presented to the message notify user routine. The field MNPLMSGOUSERDATA contains this data. You can also use the IXCMSGC QUERYMSG service to retrieve this data. The field MQAMOSUSERDATA in the answer area contains this data.