Each reactor design is given a three-character designation consisting of: * A letter for the type of ship the reactor is intended for ("A" for aircraft carrier, "C" for cruiser, "D" for destroyer, and "S" for submarine) * A consecutive generation number * A letter for the reactor's designer ("W" for Westinghouse, "G" for General Electric, "C" for Combustion Engineering, and "B" for Bechtel) For example, a S9G reactor represents a submarine (S), ninth-generation (9), General Electric designed reactor (G).