Unspecifies happens because the aircraft.cgf file does not have the following line:
ui_manufacturer=Cessna
Cessna is the example. If the plane you are using is say, the 767, then it would be
ui_manufacturer=Boeing
That makes the airplane appear under the Boeing or whichever you specify list on the Select Aircraft Menu.
As for the Experimental part of ATC i think is because this line isn't there:
atc_id=N700MS
Or you may not have chosen anything on the Aircraft menu again. I am not so sure about the second one. Correct me if Im wrong. After all, im only human
