Answer:
For officers, they seem to have followed US Naval rank, at least loosely, as I cannot recall any characters holding the rank of Lt. Junior Grade (they seemingly skip that, going from Ensign to full leiutenant), or any of the rank of Rear Admiral (again, seemingly going from Captain to only 2 degrees of Admiral, Fleet and Command, however, even by current US standards, all Admirals are addressed simply as Admiral)