DS Universe question

All the talk about the 'Hammer's Slammers' universe has reminded me of a
question that has plagued the gamers in my area about the 'Dirt Side II'
universe for quite a while.  Everyone hang on.	Since the NAC is
basically the British Empire and the United States is basically in their
domain, are "American" ships referred to as U.S.S. or H.M.S.?  Just
curious.