I can't quote a specific document other than the NROTC homepage. Howver, when I was stashed at the old NROTC unit I was assigned a bunch of projects with the Recruiting Offcer. He gave me a run through.
The Navy now has a "tiered" system for degrees-1st, 2nd, 3rd. 1st tier are engineering majors the Navy finds very applicable, i.e. electrical, mechanical, aeronautical etc. 2nd tier degrees are for engineering degrees not as desirable i.e. industrial engineering (aka imaginary engineering

), biomedical, and manufacturing.
3rd tier degrees are everything else. I have an informal piece of evidence on this as well...a friend who was recently in A-pool when they made everyone get stash jobs was sent to work at NETC. He worked directly with the scholarships and said the initial screening was separating people simply by what they marked for what they intend to major in.
This information pertains, however, to 4 year scholarship applicants.
Oh one other thing...when I was in NROTC, we were told they actually had a document/form or something that told them how to weight an engineer/science major's GPA and give them an 'equivalent' GPA. Don't know the truth to that, thats what the instructors said when some people were worrying about their GPAs for selection and 3 yr scholarships.