Wiring diagram terminal codes

My apologies if this is a FAQ; I did a fair bit of searching, but maybe I just need to know better places to look.

I can find wiring diagrams aplenty, e.g. http://zeroreality.net/prius/repair/Wiring Manual.pdf (warning: 390 page PDF; slow loading from here; may freeze your browser for a few tens of seconds). In it, I find tantalising information, like about a dozen wires coming from MG1 and MG2 to the appropriate ECU. Wires have codes, such as GSNG, which likely stand for something useful (one of the Gs is probably for Generator, but the other three would be a complete guess). I found this text in the "Abbreviations" section:

The titles given inside the components are the names of the terminals (terminal codes) and are not treated as being abbreviations.
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Ok, so I don't find it in the Abbreviations section; is there somewhere else where there is at least a brief description of each terminal code? As an example, I'm considering the possibility of driving a Prius motor from a particular controller, but that controller requires three position sensors when driving a BLDC motor. Maybe these sensors are built in, and maybe these wiring diagrams would at least give me a strong clue as to whether this might be the case or not. But only if I can understand the terminal codes.

Has anyone found a list of these terminal codes?

Thanks in advance for any information.