First letter: general type of vessel: e.g. carrier, battleship, frigate, ...

Following letters: specify further what type of vessel is being coded

• CA: Cruiser
• CH: Heavy Cruiser
• CL: Light Cruiser
• CG: Cruiser, Guide Missiles

Aircraft Carriers could have been given the code CA, which was already taken. Hence, CV was used.

• CV: Multi-purpose Aircraft Carrier
• CVN: Multi-purpose Aircraft Carrier, with Nuclear propulsion
• CVL: Light Aircraft Carrier (TBC)
• CVS: ASW Support Aircraft Carrier (Anti Submarine Warfare)
• CVA: Attack Aircraft Carrier
• CVHE: Escort Heli Aircraft Carrier

The letter 'S' was prefixed to indicate spaceflight capable vessels.

SCVN: Space Multi-purpose Aircraft Carrier, Nuclear