Motoplat coil polarity

I have two Motoplat 12 volt coils, but can't tell which terminals are pos and neg. There are two markings: 1 next to one, 15 next to the other. Anyone know how to tell which is which?
Doug

This is likely DIN72552

Yep as stated already, 15 is the hot feed and goes to the kill switch via the ballast resistor (if you have points) or to the black wire on your electronic ignition.
1 goes to the BY or BW (if you have points) or to earth if you have electronic ignition.

Two things to check:
1 ) that the mounting lugs of the coils are not grounded directly to either of these terminals.
2) the coils have the correct primary resistance (about 1.8 ohms each)

...motoplat make a lot of CDI ignitions for negative earth bikes, so it is worth checking these two aspects before fitting.

I have positive ground. The DIN 72552 code 15 says it is pos (+) from battery. This looks like coil is for neg ground system. Will it run OK if If I match battery + to the 15 terminal?
Thanks
Doug

In your case +1 will be battery negative and #15 will go to the positive end (ignition switching to ground). In reality, the difference isn't earth shaking anyway, it'll work in either direction.