BOOL IS_NAVMESH_LOADED_IN_AREA(float x1, float y1, float z1, float x2, float y2, float z2);
Returns whether navmesh for the region is loaded. The region is a rectangular prism defined by it's top left deepest corner to it's bottom right shallowest corner.
If you can re-word this so it makes more sense, please do. I'm horrible with words sometimes...