A machine-readable coding system which uses a pattern of bars and empty spaces to convey a specific meaning. The system is commonly encountered in grocery stores and other retail establishments, where the bar code is read with a scanning device. The system usually calculates the bill, corrects the inventory of the item, and carries out other management and accounting functions. Bar codes are being standardized in the hospital industry for such purposes as recording the receipt of materials and supplies purchased by the hospital, maintaining their inventory, and making charges for them. Other hospital applications include recording services (such as in the laboratory or emergency department), posting the charges to the patient bills and to the appropriate revenue and expense accounts, and inventory control. When so used, the bar code is an input device for a point of sale system. An example of bar coding can be found on the back cover of this book, on which this book’s ISBN number is displayed in both human-readable and machine-readable bar code formats.