As far as I know, Jideco made switches for Nissan and Datson. But unless you know the make and model, that won't help much. B terminal should be the battery POSITIVE. Acc is going to be the Accessory terminal, (radio, and that sort of thing. Items you want powered, without the main ign being hot at the same time.) The rest, I don't know for sure. If you have a voltmeter or ohm meter, you can sort it out using the 'B' terminal as the battery POS and seeing what other terminals are hot in the OFF position. And what becomes hot as you go from OFF to ACC, Off to RUN, and OFF to START. Write it down as you get the results of each position and it will start to make sense as you proceed. The R1 and R2 could be a couple of things, depending if they come on together, or if one comes on when the Run position is selected, and the other comes on in the START position, (so both would end up being on in the START position). If this is the case, the switch likely came from a "points distributor" system. Can still be used on anything though. If R1 and R2 both come ON in the RUN position, but show no change when START is selected, you will need to go one step farther to see what they were meant for. Using an Ohm meter, and the switch in the off position, check across the R1 and R2terminals, if the meter shows something, they are connected and are just pick up points for power to what ever needs it when in the RUN position. But, if nothing happens on the meter, they are open and not connected. You can likely use one of them for the ign coil, and the other for the alt field circuit. Since they are seperate, you won't get the power feedback from the alt to the coil that keep the engine running, even when you shut off the ign switch. Saves having to put a diode, or relay, in the alt field wire to keep this from happening. The rest you'll have to sort out and see what happens as you go. With so many variations available I could be a way off in left field, but I think this is what you will find.