I wired up a "mock" control panel back in November (successfully, I might add

. Now that I'm finally nearing the end of construction, I'm back to wiring the actual "production" control panel. But now I can't remember how I wired up my mock panel and I can't find any documentation. My question:
--The cherry switches have 3 "prongs". The single prong is used as the ground, correct? I daisy-chain that to all the other switches and then connect that to the ground on the iPAC. One of the "pair" prongs is the wire-directly-to-the-iPAC, correct? So what's the other prong for?
Thanks!