Problems: Warehouse inventory control of rental machinery is complicated because it involves many different items. For example, it is necessary to keep track of which machinery has been rented out, which machinery has been returned, and what condition the machinery is in (e.g., how clean it is). Clerical errors can occur in management systems based on hand-written forms. Collating all the information into, for example, daily or monthly reports can be very difficult. Perform inventory control using ID Tags mounted to the machinery. Write information about the machinery, such as the machinery number and the status of the machinery (e.g., reserved/available, processed/not processed after return, clean/dirty), to the ID Tag.