Wiring diagram decoding

[yosamitysam]

Help a dummy out here: what are the letters referring to like -X55, -X4? Or the ones that say GT/6 and the like? And finally, the lines that lead off to the right to '/2.E1' and the rest, what is that?

Thanks a ton for any help

[InRoostWeTrust]

The S23 and S10 designations are described for the item on the last sheet of that sections schematics list - like 'starter' solenoid's or 'lighting power relay'.
Don't always trust the color code, but the schematic is generally true. The very last page of the schematics provides a legend for the wire colors and abreviations.