cd player stalk control

[denton92]

hi everyone, im looking at a new head unit but want one with that steering wheel stalk control that will connect up to the standard one with the ds3, ive found a decent head unit but it says under the steering wheel control function bit 'the function can only work with the the car which has the "analog-to-digital conversion" control system'
does anybody know what this analog to digital conversion is or what it means? im guessing its about a DAB radio or something?
thanks.