What is a suffix for submarine?

The codes are- for conventional () non nuclear powered) Submarines- SS ( for example the U.S.S. is SS-297. Atomic subs are SSN or SSBn - BN if fitted for Ballistic missiles such as the Polaris or Trident types ( there is no Submarine Called the Polaris- it is a guided missile!) so SS- submarine, SSN- Nuclear submarine- SSBN- Nuclear submarine- Missile type.