to confuse friendly ships with German U-boats. For similar reasons "V" was not used. Pendant numbers 00–10, 13, and those ending in a zero were not allocated to flag inferiors. C ("coastal") — (pre-war construction) F ("fleet") — H — H class L — L class M ("minelayer") — P — O class, P class 31P— U class (wartime construction), V class 211P to 299P — S class (wartime construction) 311P to 399P— T class 411P to 499P— A class 511P to 599P— United States Navy lend-lease submarines 611P to 699P— commandeered foreign construction 711P to 799P— captured enemy submarines R — R class S — S-class submarines (pre-war construction) T — T-class submarines (pre-war construction) Post-1948 After the Second World War, in 1948, the Royal Navy adopted a rationalised "pennant" number system where the flag superior indicated the basic type of ship as follows. "F" and "A" use two or three digits, "L" and "P" up to four. Again, pennant 13 is not used (for instance the helicopter carrier was followed by ). A — auxiliaries (vessels of the Royal Fleet Auxiliary, Royal Maritime Auxiliary Service, and Royal Navy Auxiliary Service, including depot ships, boom defence vessels, etc.) C — cruisers (currently none in service, therefore unused) D — destroyers F — frigate (former escort destroyers, sloops and corvettes) H — shore signal stations (military); survey vessels K — miscellaneous vessels (e.g., the seabed operations vessel or the helicopter support ship ) L — amphibious warfare ships M — minesweepers N — minelayers (currently none in service, therefore unused) P — patrol boats R — aircraft carriers S — submarines Y — yard vessels Flotilla bands 1925–1939 From 1925, flotilla leaders were issued with but did not paint on pendant numbers. Instead, a broad band deep was painted round their fore-funnel. Divisional leaders wore a pendant number and had a narrower deep band on the fore-funnel, painted from the top. The Mediterranean Fleet wore black leader bands and the Atlantic – later Home Fleet wore white bands. The flotillas wore combinations of bands on their after funnel to identify them. From 1925 the following bands were worn; 1st Destroyer Flotilla — one black band 2nd Destroyer Flotilla — two black bands (one red from 1935) 3rd Destroyer Flotilla — three black bands 4th Destroyer Flotilla — no bands 5th Destroyer Flotilla — one white band 6th Destroyer Flotilla —