Control-C else, typically returning control to the user. Ctrl-C was one of a handful of keyboard sequences chosen by the program designers at Xerox PARC to control text editing, with Ctrl-Z (Undo), Ctrl-X (Cut), Ctrl-V (Paste), and Ctrl-P (Print). The first four letters are all located together at the left end of the bottom row of the standard QWERTY keyboard, and P towards the upper right. The equivalent key combination on Macintosh computers is Command-C. Control-C as an abort command was popularized by TOPS-20 and TOPS-10 and adopted by other systems including Unix. It was also adopted by Digital Equipment operating
Thumb-shift keyboard with the use of thumb-shift key on the same side of the keyboard relative to the key. Thumb action of the opposite hand (known as "cross-shifting") is used to type the characters representing a voiced sound, written in hiragana by adding a diacritic mark (dakuten) on the corresponding voiceless sound characters. This has an advantage in memorization because it is not necessary to memorize two positions. For example, take the home position of the right index finger (letter 'j' in QWERTY). Without thumb action, it is 'to' (と). It is 'o' (お) with the right thumb shift and 'do' (ど)