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
QWERTY based partly on QWERTY and is claimed to be easier for an existing QWERTY typist to learn while offering several supposed optimisations. Most modern computer operating systems support these and other alternative mappings with appropriate special mode settings, with some modern operating systems allowing the user to map their keyboard in any way they like, but few keyboards are manufactured with keys labeled according to any other standard. Comparisons have been made, between Dvorak, Colemack, QWERTY, and other keyboard input systems, namely stenotype or its electronic implementations (e.g., Plover an opensource project ). However, stenotype is a fundamentally different system,