Three types of mobile digital equipment are included: devices that transmit and/or receive preformatted messages, devices that transmit and receive randomly composed messages using a keyboard and either a hard copy or soft copy display, and devices that receive randomly composed messages and use either a hard copy or a soft copy display. The standard defines 22 principal terms; lists specific requirements for performance, test sequence, user information, environmental characteristics, etc.; and explains test methods. Tables, figures, footnotes, six references, and a six-item bibliography are included.