What forces GSX to use a specific AFCAD? Can it be changed?
It simply respect the same rule as FSX: the file used for any given airport will be the one with the highest priority in the Scenery Library.
What are the attributes GSX looks for before it chooses the AFCAD to use for a specific airport?
The file must include at least one parking, and it must be connected to a taxiway and they must be on the same file, these are the requirements for an AFCAD to be usable.
So, for example, if you have an enhancement AFCAD, which ONLY adds some parkings, but it relies on the default one for the taxiway layout and the runway, it won't be used by GSX, which will revert to the default one, even if it's not on the topmost layer.
