The event raised has some information in it that may be worth mapping back into the workflow engine. The event has both primary and secondary event data. The primary event data is what was used to match the event in the first place so there is little point in mapping this back into the process. The secondary event data however may be unknown to the workflow engine and so can be mapped in. Also since an event wait activity can wait on any number of events, the actual event that was raise may be of interest and so can also be mapped into the workflow engine. Finally, the Cúram user raising the event might be of interest and so this can also be mapped into the workflow engine.
It should be noted that if an activity instance should wait for all of it's associated event waits to be matched, any event output mappings that exist for the activity instance will be processed each time an event is raised that matches one of the event waits.