Omron Switches on MTU

I'm struggling to understand how the V-156-1C25 switches get wired and what purpose they serve. I think I would maybe understand the wiring if I understood the purpose. Basically for the purpose of labeling the cables as i'm nowhere near wiring this thing up yet. As I understand the common terminal is basically a positive connection and then 2 negative connections running to the arduino. I guess maybe somebody in here can explain the purpose of these particular switches, i'm not very familar with SPDT switches