 The designation "F-117" seems to indicate that it was given an official designation prior to the 1962 U.S. Tri-Service Aircraft Designation System and could be considered numerically to be a part of the earlier "Century series" of fighters.The assumption prior to the revealing of the aircraft to the public was that it would likely receive the F-19 designation as that number had not been used.However, there were no other aircraft to receive a "100" series number following the F-111.