The “six-bit-code” is just a barcode of black or white paint streaks, that encode a lens-ID, so the camera can understand which lens is mounted and can store things like maximum aperture and focal length in the EXIF, but this is not a way to communicate parameters that vary per shot like aperture and subject distance. Unless there are actually electrical contacts then there isn’t any variable information that can be communicated.
http://vimeo.com/26251829 (from http://overgaard.dk/leica-50mm-Noctilux-M-ASPH-f-095.html )
