Actually, there are three events likely to appear as DON'T USE for you. I shall list them in order of how likely they are.
#1, obviously, is the trigger zone. It is like a trigger crate, only can turn triggers off, and doesn't work with TriggerID0 (anyone have some logical ideas on why?). J2O, among other places, has a JCS.ini with it.
#2 is the Pacman/Blue Ghost enemy, which only works in TSF, and acts like a Spark. I think JCSRef has a JCS.ini with it.
#3 is an airboard event which you can set the generation time but doesn't work in multiplayer. (however, if you're going to make an airboard test, put some in for all the poor people who are just testing it in SP) No JCS.ini (other then my own) as far as I know has it, but it's event number 243 if you want it.