Ford wiring diagrams - translation

I have a CD that 'shows' the wiring diagrams of several Ford cars, and specifically my diesel Ford Focus.

The diagrams are loaded with codes and letters which identify electrical items, perhaps their locations and also the conductors/wiring between them.

Problem is I can't translate the codes / abbreviations. Can some kind folk point me to a source where I can read about the codes letters etc that Ford uses in it's wiring diagrams.

Thanks folks. John Hewitt, Malaga, Spain