Reason I was curious about this is because i cant load from the side door of the 747 as gsx thinks thats a pax door
GSX doesn't think it's a passenger door.
The Main Cargo door is recognized as a proper cargo door, and with the latest GSX, we added the ability to set it independently from the other cargo doors. Before, you were required to forego one of your right cargo doors and move it to the left, now the Main cargo door has its own separate entry.
Right now, it's used only at the KSDF UPS Stands, which will use it automatically, but ONLY if the airplane is one that can use the cargo stand as such, so it must have a forward main cargo door, which excludes the 747 or the 777.
The next GSX update we are already working on, will finally allow for a 3rd Cargo Loader, dedicated to the Main cargo door, so you'll be able to use it everywhere ,with any airplane that has one (a 747 won't still be able to use it at the UPS Cargo Stands though), with 3 loaders working at the same time.
This was all planned, but we didn't want to delay the KSDF release further, so we left out the 3rd cargo loader from GSX, but it will arrive fairly soon.