This might be a dumb question, but when I read old threads on cables for Series basses there are a lot of recommendations about four-conductor (star quad) cable. When I look at the couple of diagrams for the connectors, there are wires to each of the five pins (ground, neck pup, bridge pup, + and -).
So for the potentially dumb question: if the cable has four conductors, where does the fifth one come from???