Can someone explain the purpose of the unit properties in Trigedit? If I was just to take a wild guess I would have to say that it's only for pre-placed units?
You can create a unit with properties through triggers basically what it does is add stuff like invinciblity or cloak ect.
You can have 64 max unit properties units via triggers. Trigedit actually has a pretty good method for doing them compared to other editors, not that it couldn't be improved.