Wiring diagram of this blue 12V switch?
In electrical engineering one might call it:
DPDT (Double Pole Double Throw) Momentary (On)-Off-(On) Reversing Polarity Toggle Switch.



Momentary in this configuration means that it's spring loaded towards its centre position.

Edit: I'm not sure though, see the comment below. I have the remotely controlled switch points from the gray era and they work like above.