The Postal Service uses a variety of systems to determine the asset quantities at which a replenishment action is placed. Although some of these systems utilize complex forecasting methods, at its simplest level, stock is replenished using a reorder point (ROP) process also known as the “perpetual inventory system.” The computer system in use tracks on-hand and on-order real assets. This figure is compared with a calculated asset balance at which the combined ordering, fulfillment, and shipment times would indicate an order should be placed. When assets are at or below a certain ROP, a quantity is reordered to replenish the stock, based on authorized stock levels. In theory, when assets are at the ROP, the stockroom holds just enough stock to cover predicted usage while the order is being processed and shipped, plus emergency stocks.
