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 international standard ISO/IEC 9995-2, although this is not explicitly required by the US American national standard. US keyboards are used not only in the United States, but also in many other English-speaking places, including India, Australia, English Canada, Hong Kong, New Zealand, South Africa, Malaysia, Singapore and Philippines. However, the United Kingdom and Ireland use a slightly different layout because of the Irish language. The US keyboard layout has a second Alt key instead of the AltGr key and does not use any dead keys; this makes it inefficient for all but a handful of languages. On the other hand,