As you know, units typically stand on the roadWay LOD, and if it doesn't exist, they stand on the GEOM LOD. So a command like this:
lineIntersectsSurfaces [top, bottom, objNull, objNull, true, 1, "ROADWAY", "GEOM"]
can give the next surface where you can stand on.
It is very useful when you want to place something on top of another object.
Unfortunately, right now you have to create a helper object, use setPosWorld to place it where you want, and then use the getPos command to get the diff to the roadway LOD. This is extremely slow and very limited.