There are at least three different kinds of signals in that picture. I assume you are asking about the ~2.5 kHz wide signals in your screenshot.
The ones at 6390, 6408, 6411, and 6435 kHz (all center freqs, not tuned freqs) are all STANAG 4285 modems. Most, but not all, 4285 is encrypted. In some circles they just call this "STANAG" and be done with it (notice the "STANAG" on the labels across the top of the waterfall), however that is not a good way to label these. There are multiple types of STANAG signals, not just 4285. STANAG 4285, 4481,4529, and 5511 are the most common to see in the HF region, and each is different. 4285 and 4529 look somewhat similar, but are different, and 4481 and 5511 look nothing like the others.
STANAG is simply a STANdardization AGreement within NATO. There are STANAGs for everything from bullet specifications (7.62 NATO round, or .308, is STANAG 2310, the 5.56 NATO round, or the M-16 .223 round, is STANAG 4172) to how to handle food, how to write intelligence reports, what symbols to put on maps, how to handle captured enemy documents, pretty much every military activity or hardware you can think of has a STANAG addressing it. And of course communications must be covered.
T!