Bosch ignition coil terminal identification

[droptop]

I'm commencing work on my new spider project and the first item of business is changing the coil.
The car had a Ford coil with the ford bullet style connections connected to the original spade terminals via insulating tape so at least the original terminals are still intact.
Anyway, I have two Bosch coils of the correct type but instead of "+" and "-" they are marked "1" and "15" and even the wiring diagrams show the polarity as symbols rather than the numbers.
Can anyone tell me which is which?
Thanks

[HFStuart]

15 is +ve
1 is -ve

[droptop]

Thank you kindly.
That will simplify things, that and leaving the homemade immobiliser that was causing the intermittent spark failure disconnected!

[lukasdeopalenica]

Usually 15 is a battery +
These markings come from DIN (Deutsches Institut für Normung) and there you can find more electric terminal markings:
http://en.wikipedia.org/wiki/DIN_72552
In case of ignition coil it is supplied through an ignition switch