Substitute character actions than the last one can also be undone by pressing multiple times. was one of a handful of keyboard sequences chosen by the program designers at Xerox PARC to control text editing. Presumably these particular keystrokes were chosen because of their location on a standard QWERTY keyboard, since the Z (undo), X (cut), C (copy), and V (paste) keys are located together at the left end of the bottom row of the standard QWERTY keyboard. Substitute character A substitute character (␚) is a control character that is used in the place of a character that is recognized to be
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