What features should a map format support?

[Renegade]

For one of the "OMG I'm gonna make my own game!!!1!!11" plans we all inevitably did develop, do develop or will develop, I'm currently pondering what kind of features or attributes a map format for an RTS has to support. Since we have a mapper or two walking around here, I thought I'd ask the rest of you

This is dream time, so you can come up with basically anything you miss in YR. You can assume basic general concepts as planned, I'm looking more for distinct features I might otherwise forget - think "tunnels" as opposed to "different height levels" or "a trigger that allows to conditionally turn a unit into a banana" rather than "a way to script the map".

For example, one thing I'd come up with ad hoc are cover zones like in Dawn of War - for those who don't know it (shame on you - go buy it immediately! Yes, I said "buy"), in DoW, there is a way to set up areas like craters or trenches to reduce the damage you take from long range weapons (since you're covered), while, on the other hand, allowing areas that multiply the damage taken, for example fords (since you're exposed and largely immobile).

Stuff like that. Or native day/night cycles. Evolving cities. Neutral entities engaging in explicit sex acts in the streets. Whatever you can come up with.

Tell me Please

[MRMIdAS]

Civillian cars that are roadbound like trains