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
Chorded keyboard application ComboKey Plus enabling e.g. one-hand typing. The EkaPad is a 12-key chorded keyboard operated with the four fingers of one hand. It is supported on the thumb. With the 9 main keys, (operated by the index, middle, and ring fingers), 2 prefix keys and one delete key, the EkaPad can produce all the inputs of a standard qwerty keyboard with one, two, and a few three finger chords. For some characters one or two prefix chords are required. 9 main keys (3×3 matrix) can produce a total of 511 chords. With each of the three fingers limited to its