One of these had been used by Rommel during his NA Campaigne. In one mission, his Storch seen coded with CB+TL. This appeared to the fuselage as well as underside of wing. For the Stammkennzeichen ie,"four letter factory codes", this Database project remains very handy and useful . "The LEMB Stammkennzeichen Database Project". For more infos on Storch .. "Lexikon der Wehrmacht-Kampfgeschwader z.b.V.323 and "Neue Site 26-Lexikon der Whermacht".