It is a SPDT momentary switch.
Here is a pic of a word doc. Please know that this is my version of what Bob at Aeroelectric came up with. It is an excellent device. There is also tons of helpful info on JD Newmans website as listed.
My experience, do not use Latching relays by their vary design they use latching relays. You have to manually reset them.
This does not have the reverse polarity protection diode on it as in the PCB show. FYI only.