Yup....think of it this way (in SAE terms): 6/16" = 3/8" Meaning, #6, or 6/16", is what we call a #6 fitting. #4 is 1/4", or 4/16". All of the AN fittings are measured in 1/16ths of an inch.
Thank you, that helped a lot.
I think US should change to the metric system, that would make my plumbing MUCH easier ;-)