The thing is, people start these music events out of whatever vision they have for them, based usually on whatever they have experienced themselves that someone else had started and however it evolved. So the events are going to tend to vary, no matter what they are called. If you have a general idea what a thing is, but then try to impose rules and expectations based on how YOU understand the thing is "supposed" to go, there can be hell to pay. So general guidelines are helpful but just seeing how a thing works for yourself, and asking a few questions, is probably going to be just as accurate if not more so.