The "we can tell you, but we'd have to kill you" BS is getting very old. There is one wire emerging from the pickups. That de-facto means that mechanical contact along the path to the nearest circuit ground (the little PCB on the trem block) is the ground scheme. You can claim trade secret, voodoo or anything else you'd like to, but that doesn't alter the laws of physics. Sorry to be testy, but this answer comes across as more condescending than usual and I'm tired of biting my tongue.