The RST coding is something I wondered about ever since I first saw those designations on some European test equipment when I was a kid (thinking back on it, I reckon it must have been a phase rotation tester).
It's certainly strange to those of us who are used to seeing A,B,C, or L1,L2,L3. Still, I suppose the R,Y,B (red, yellow, blue -- phase colors) seen sometimes in British circles would seem strange to outsiders.
