Question about the 1985 Ibanez RS 440 guitar...?

I have an old Ibanez RS 440, the same one featured on "Back to the Future" that Marty plays auditioning for his school dance. lol... anywho, I can't seem to find an original wiring schematic for it. There is a small two-position toggle switch between the Tone knob and the Pickup selector/5-position switch.... can anyone tell me what the switch was originally supposed to do? Right now, that switch isn't connected to anything, it is simply there for cosmetic purposes to fill what would otherwise be a hole in the body. If I knew what the switch was for, then I could wire it up, but.. I'm stumped.