I was looking at bass bodies, and came across this puppy. While I like it for building a "telecaster" bass, I also am a bit confuzzled. What is this routing for? I'm assuming it's for a pickup. Apparently I live under a rock, and have no clue what kind of unit would fit in there. I'm almost sure that if/when it's explained, I'll do a facepalm and go Doh!