Several trainer things were turned into special names in RCT3, (Unlimited height and Chainlift/brake speeds).
I don't know about any 'Zero-Clearence' However, most CS is made without collision.
I also set all the helpful cheat names up as a peep group in the Peep Editor.
Here's a list of cheats... http://rctgo.com/games/rct3-cheats