Here is the latest version of the National Security Agency's unofficial org chart, a mind map I have been updating ever since Edward Snowden made it cool to obsess about the NSA. My goal is to turn the map into a functional description of how NSA works, not just what NSA is. It's a work in progress.
It's difficult enough to keep track of all the cover terms the NSA uses for databases, systems, and intercept points, but it's almost impossible, even given a wealth of classified documents, to figure out how these discrete entities relate to each other. The NSA's FISA collection adds a another dimension of complexity.
In general, the chain of signals intelligence, excluding FISA, operates this way:
Analyst figures out whom to target, or gets an order to target someone....