The four-digit numbers in column two are Lockheed Martin´s F-22 construction numbers, beginning with 3999 and 4000 (used only for static tests), and followed by Raptor 4001 as the first flyable test aircraft. For their military serial numbers, USAF just adopted the construction numbers and combined these with the last two digits of the related fiscal years as prefix, beginning with 91-4001 for Raptor 4001. The numbers in column one of the Japanese source are the shortened serials, painted on the tails (but in reality without the hyphens), beginning with AF99 001.
