For example, Project 641 had no other name, though NATO referred to its members as s. The ship classification in Russia (and formerly Soviet Union) does not completely correspond common designation, particularly for destroyer, frigate and corvette type ships. Russia has own classification for those ships. In Russia, there is a class of Squadron Torpedo Carriers () that traditionally is adapted as Destroyers (formerly torpedo boats destroyers). The Russian corresponding word for destroyer is used in air force for fighter aircraft. Also destroyers could be classified Russian Big Anti-submarine Ships () or Big ASW Ships (e.g. Udaloy-class destroyer). At the same time Big Anti-submarine Ships could also be classified as cruisers (e.g. Kara-class cruiser). The Russian Big Anti-submarine Ships class also has its sub-class of Guard (or Patrol) Ships. The Russian Guard (or Patrol) Ships () traditionally are reclassified as frigate (e.g. Gepard-class frigate). Another substantial class in Russia (and formerly Soviet Union) is Small Anti-submarine Ships () or Small ASW Ships and are adapted as corvettes (e.g. Grisha-class corvette). As corvettes were adapted Russian Small Missile Ships (; e.g. Buyan-class corvette) or Missile Boats (; e.g. Tarantul-class corvette). The British Royal Navy has used several methods of naming classes. In addition to the accepted European convention, some classes have been named after a common theme in the included ships' names, e.g., s, and some classes were implemented as an organizational tool, making traditional methods of naming inefficient. For instance, the is also known as the A class. Most destroyer classes were known by the initial letter used in naming the vessels, e.g., s. Classification by letter also helped to conflate similar smaller classes of ships as in the case of the C-class destroyers of 1913 whose names spread across the alphabet. Since the end of the Second World War, Royal Navy ship classes have also been known by their type number (e.g. Type 42 destroyer.) In the United States Navy, unlike most other navies, the first ship in a class to be authorized by Congress is the designated class leader and gives the name to the class, regardless of the order in which the ships of that class are laid down, launched or commissioned. Due to numbering conventions the lead ship almost always has the lowest hull number of her class.