A typical two pick-up guitar normally has a three position switch. Up (toward the player is generally the neck pick-up-typically used for mellower tone. The middle position is for the combination of the neck and bridge pick-ups-for "middle of the road" tones. The "down" position is the bridge pickup. It's for brighter-harsher tones. On a Fender Stratocaster-with three pick-ups, the five positions are various combinations of the three pick-ups. There are lots of other options. Some guitars have more than three pick-ups. Some are a combination of traditional pick-ups and piezo (microphone-type) pick-ups-sometimes one for each string, with separate outs or a blend, to either approximate an acoustic sound or a blend of acoustic and electric.
Then, add out-of-phase switches, to place the pick-ups out of phase with each other, for different sounds, and single coil and dual coil switches (Fenders generally have single-coil pick-ups; Gibson guitars have double-coil pick-ups), and it's easy to see how a real tone freak could have a guitar wired for 11 (or more) pick-up positions.
I have one double-neck that has one three-way switch for neck selection (either or both), two three-way switches for pick-up selection on each neck, four phase switches -one for each pick-up and 4 coil taps for single-dual coil selection, plus two pre-amps and adjustments for piezos.
Steve Howe is a monster, and has developed his own pick-up and wiring system. Whatever it is, he sounds GREAT!
Russ
[This message has been edited by captain Russ (edited 08-17-2010).]