The default behavior when no Deice areas has been defined in the GSX airportprofile, is to allow you calling Deicing from anywhere, as long you are not locatedin a parking spot
Custom Deicing areas are like special kinds parking spots, where the only serviceavailable is Deicing, and can be performed with engines running. They are notlocated in the scenery itself, so only GSX knows about them, and don’t have anyconnection to the rest of the airport layout or are affected by the scenery used.