I propose we add the property broadcastOfEvent to BroadcastEvent to allow authors to specify when a broadcast is of an event rather than a creative work.

BroadcastEvent currently has the property workPerformed for broadcasts of creative works like movies, tv programs, etc. While I understand some consider antelopes to be documents, it is odd to consider an event like a sports match or an awards ceremony as a CreativeWork.

One might be tempted to use subEvent or superEvent, but those don't seem appropriate either. A live broadcast is neither part of nor a parent of the event itself.