Command key keyboard of the NeXT Computer that key was marked in green. The menus were not marked with a symbol denoting the command key. Besides being used as a modifier key for keyboard shortcuts it was also used to alter the function of some keys. toggles alpha lock, sends Enter and toggles Mute. The functions were printed in green on the front side of the modified keys. This was also done on the Z, X, C and V keys (Undo, Cut, Copy and Paste). On the NeXT ADB keyboard, the Command keys were replaced by keys labeled and the Command key
Fn key Fn key in Mac OS X. Fn is a modifier key, and works like other modifiers keys, such as Ctrl, Shift, Alt and AltGr. For a standard modifier key, the microcontroller inside the keyboard sends a scancode for the modifier itself, which is then interpreted by the operating system and combined with other simultaneous key-presses. The Fn key is a form of meta-modifier key, in that it causes the operating system to see altered scancodes when other keys on the keyboard are pressed. This allows the keyboard to directly emulate a full-sized keyboard, so the operating system can use standard