US Patent 7231166 Consumable goods management system

The present invention provides a consumable goods management tag, comprising: a rewritable memory for storing remaining quantity data representing a remaining quantity of consumable goods, and a rewrite controlling unit for controlling a rewrite of the remaining quantity data stored in the memory on the basis of a remaining quantity data writing request inputted from outside, carrying out the rewrite of the remaining quantity data responding to increase of the remaining quantity only when a predetermined rewrite condition is fulfilled, and carrying out the rewrite of the remaining quantity data responding to decrease of the remaining quantity even when the rewrite condition is not fulfilled.