began as a naval aircraft, the RAF kept the name and it also has a single set of numbers. The post-1948 mark numbers are variously presented in full (e.g. Hercules C Mk 3) or abbreviated (e.g. Hercules C3) forms, and either with or without a full stop between the prefix and mark number. The use of the "Mark" or "Mk." has gradually been dropped. Other designation systems used for UK military aircraft Specification numbers From 1920 to 1949, most aircraft had an associated Air Ministry specification number. Prototype aircraft would be produced under contract and would be referred to by Manufacturer Name and Specification Number. If accepted they would get a service name. For example, the "Fairey 6/22" was built to meet the 6th specification issued in the year 1922; it was accepted as the Fairey Flycatcher. Later, a preceding letter was added to the Specification Number to identify the type of aircraft; e.g. specification B.28/35 for a bomber was the 28th specification issued in 1935; in this case the specification was specifically written for the Bristol 142M, a modification of Bristol's Type 142 private venture civil aircraft (Britain First) for military use as a bomber, which would enter service as the Bristol Blenheim Mk 1 light bomber. Manufacturers designations From about 1910, the largest single designer of aircraft for the British Army's Royal Flying Corps was the Royal Aircraft Factory. The Royal Aircraft Factory designated its types according to either the layout of the aircraft or its role – e.g. Royal Aircraft Factory S.E.5, the "S.E." prefix representing Scouting Experimental. In practice successful Royal Aircraft factory designs were largely built by other manufacturers though still known by the Factory designations Some examples of manufacturers designations and the corresponding service designations are shown below: Avro 549A = Aldershot II Vickers VC10 Type 1180, the tenth "Vickers Civil" design, were (Type 1106) VC10 C1 transports converted to have additional tanker role; known in service as Vickers VC10 C1K Westland WAH-64 Apache = Apache AH1 US designations For some aircraft types (e.g. the C-17 which is currently known in RAF service as the "C-17 Globemaster III" ) the UK armed services have used the US designation rather than assigning their own designation. See also United Kingdom military aircraft serials Japanese military aircraft designation systems United States Department of Defense aerospace vehicle designation Soviet Union military aircraft designation systems List of aircraft of