Ah, Richard, you would not believe the potential hornets' nest that your innocent question might disturb ...

. I freely admit it's one of the reasons I haven't replied before now

. But here goes ..
First off, I'm going to assume you have one of the bullet shaped headlamps, not a pancake style. I have photos of at least half a dozen different variants of these. So let's cut to the chase ...
This is one of the more common variants you will see.
Light switch on the top, idiot lights as shown, ignition switch on the left. This is the same as what Ducati Vintage Store sell, btw. Note however that the idiot lights are sometimes reversed - see the second photo.
Headlamp from Italian Motorbikes com 1a.jpg
Headlamp from Gio 2.jpg
Moving along, here's another version, this time without the light switch on top. And a green parking light/lens. And the ignition switch on the right.
Headlamp, eBay Feb 2011.jpg
And here with both the ignition switch and the light switch on the sides - ignition switch to the right, light switch to the left. And a green parking light/lens.
Headlamp, eBay Feb 2013 €100.jpg
I hope you're following all this ...
And here's a variant on that, with the addition of a blue indicator light. But no idea what it's for ...
Headlamp with BLUE indicator light, eBay Mar 2011.jpg
I think I'm going to stop now ...
