In the Navy we call them subspecialty codes, not identifiers, FYI. Unless you have some type of advanced degree or certification, you won't necessarily go to that area, all experience aside. Additionally, the Navy places nurses in areas according to the needs of the Navy, so even with an advanced degree, advanced certification, and 10 years experience, you can end up working in Labor and Delivery. Currently, I have 10 years critical care experince, 7.5 in ED and 2.5 ICU. The Navy sent me back to get my Master's in ER/Trauma and even though they are paying for it, I can still go to an area outside of my focus should the needs of the Navy require it. In the Navy as a nurse you need to be flexible regarding where you work. So if you're wanting to come in and work solely Oncology, I wouldn't plan on it, you may be in for a HUGE disappointment. Also, you would need to get an age waiver. Probably not what you want to hear, but that's the reality of nursing in the Navy at present. I'm happy to answer anymore question you have.