: The theories I like best are: a. the initial distinctions were made without a
: lot of data, and possibly by people not that knowledgeable of ship
: classification, and they became known enough and used enough that it was
: impractical to change them, so newly-observed ships had to be fit in in an
: awkward way
: b. the ship classes are translations

: Where do the letters come from, again (CCS, CRS, etc.)? That would really
: help in figuring it out.

The letter codes come from the mostly non-canon Cortana Letters that predated Halo and we made some new ones from that initial batch for the first Visual Guide. I have an email with their spelled out initialisms somewhere from back in 2011, but if they didn't end up in the fiction since, it's not my info to provide. 343i could still make changes from what we'd initially posited since most hasn't been used.