[marknorton]

Take a look as the M7 ISO thread, there's a picture there of the new optical sensor they use to read the DX coding off the film canister. I expect that the sensor to read the lens will be a miniaturised version looking at the coding on the lens, through a slot in the lens mount which has a flush mounted (glass/polycarbonate) in-fill.

And how many bars are there on a film can? You've guessed it, 6!