A shopping system comprising a reading device is provided. The reading device is adapted to read an interface surface provided on a product item. The interface surface has coded data disposed thereon which includes, at a plurality of locations on the interface surface, a corresponding plurality of coded data portions. Each coded data portion is indicative of an identity of the product item and the location of the coded data portion. The reading device includes: (a) a radiation source for emitting radiation such that it exposes at least one coded data portion; (b) an image sensor for sensing the exposed coded data portion; and (c) a processor for determining, using the sensed coded data, product identity data and/or position data.