Dual-state (toggle) keys should indicate their operational (functional) status.
Additional information: Dual-state keys include keys such as Caps Lock, Num Lock, Scroll Lock, and Function Lock. A common problem with dual-state keys or pushbuttons is visual identification of the position or state of the key. The preferred solution is to provide a separate indicator light for the status of each such dual-state key. When indicator lights are employed, they should be imbedded in the key, located close to the associated key, or be clearly labeled if not located close to the keys (e.g., Caps Lock icon). An indicator panel for one or more dual-state keys is also acceptable. Other means for indicating the status of dual-state keys may be showing the functional status on the receiver of a wireless keyboard or on the primary or main display.100