Projects often have multiple designators. US-984XN is the official name. Internally the collection platform (source) is referred to as PRISM (as an example, the entire U-2 program was CHESS). Each relationship with a partner probably had a code name like LONG WINTER (completely made up).
!!! WHO THE F%!# told you about LONG WINTER!?!? What do you know? Tell us now... we know you're lying dsl! Tell us everything and we'll let you live! Lie to me one more time and I'm drilling a hole through your hand with this electric drill! Who are you working with? Who's paying you? When did you convert to radical Islam? Who's your contact? Tell us now!
Who gets to choose the names? How do they prevent duplicates? Is there some approval process for names? I find this particular topic really interesting, specifically who and how a name for any top secret program is selected.
The selection process I don't believe to be public, and varies between organization. However everybody at least reserves them in a DoD database called The Code Word Nickname and Exercise Term System. Regardless of the project, code words become classified once they are exposed or no longer in use, and can be reused after two years.
