The button and indicator light code A22 is judged to be suitable for setting command, signaling only and monitoring function, can realize error-free communication between man and machine, as well as being applied to machine, system engineering equipment and devices. The structural module configuration of the A22 can flexibly adapt to different functional requirements, such as control, signal indication, selection and switching, self-locking or resetting by spring . The front element provides service colors and configurations and is applicable to different applications.