(1) Protected-type button: Features a protective housing to prevent mechanical damage to internal components or accidental contact with live parts; designated by the code H.
(2) Normally closed (NC) button: The switch contacts are closed (connected) in the normal state.
(3) Normally open (NO) button: The switch contacts are open (disconnected) in the normal state.
(4) Combined NO/NC button: Features both normally open and normally closed contacts in the normal state.
(5) Illuminated button: Contains a signal lamp; serves as both an operation control and a visual indicator; designated by the code D.
(6) Click-action button: A button operated by a clicking action (similar to a mouse button).
(7) Explosion-proof button: Designed for use in environments containing explosive gases or dust without propagating an explosion; designated by the code B.
(8) Corrosion-resistant button: Designed to prevent the ingress of corrosive chemical gases; designated by the code F.
(9) Waterproof button: Features a sealed housing to prevent the ingress of rainwater; designated by the code S.
(10) Emergency button: Features a large, protruding red mushroom-shaped head; used to cut off power in emergencies; designated by the code J or M.
(11) Open-type button: Designed for flush mounting on switchboards, control cabinets, or control console panels; designated by the code K.
(12) Interlocked button: Features multiple contacts that are mechanically interlocked with one another; designated by the code C.
(13) Rotary button: Operated by manually rotating a knob to switch contacts between "on" and "off" positions; typically panel-mounted; designated by the code X.
(14) Key-operated button: Operated by inserting and turning a key; prevents unauthorized operation or restricts use to specific personnel; designated by the code Y.
(15) Self-holding push-button: A push-button equipped with an internal electromagnetic mechanism for self-holding; designated by the code "z".
(16) Combined push-button: A push-button unit consisting of a combination of multiple push-buttons; designated by the code "E".
