Basically, here's what I want to accomplish: I want random Encounters (of a specially-prepared type, blah blah blah) to occur only at a certain height Y. I don't care if they're patrol routes or regular randoms, and I'm thinking that working with a nearly two-dimensional Eliptical Zone will do the trick.

Does anybody think this is impossible, and if yes, why? There is a very good reason for me to want to do this- if I want to see AI-controlled ships (like, the ocean-going kind) in my mod, then I need to get this to work. I've done a couple of very early experiments, but the results were inconclusive... I'll do more tomorrow, as I need to get this issue wrapped up pronto...