http://electrospaces.blogspot.nl/2014/09/about-stellarwind-and-another.html [ ... a good read; go do so now! ] for the TL;DR crowd: """ In the end, it doesn't make much difference whether STELLARWIND is a control system on its own, or a sub-system of COMINT, but it is remarkable that for such an important program, the people involved apparently also weren't clear about it's exact status and how to put it in the right place of a classification line. More important though is that the declassified documents show that besides the STELLARWIND program, there's at least one COMINT-compartment with at least one sub-compartment that protect similar or related NSA collection efforts which are considered even more sensitive, but about which we can only speculate. """