A method of maintaining a status of a product item, the product item including an associated interface surface, the interface surface having disposed thereon or therein coded data including a plurality of coded data portions, each coded data portion being indicative of an identity of the product item, the method including, in a sensing device: (a) sensing at least one coded data portion; (b) generating, using the sensed coded data portion, indicating data indicative of the product item identity; and, (c) transferring the indicating data to a computer system, the computer system being responsive to the indicating data to update product status information stored in a data store.