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
QWERTY through the key. On Macintosh computers, the "Norwegian" and "Norwegian extended" keyboard layouts have a slightly different placement for some of the symbols obtained with the help of the or keys. Notably, the "$" sign is accessed with and "¢" with . Furthermore, the frequently used "@" is placed between and . Most typewriters use a QWERTZ keyboard with Polish letters (with diacritical marks) accessed directly (officially approved as "Typist's keyboard", , Polish Standard PN-87), which is mainly ignored in Poland as impractical (except custom-made, e.g., in public sector and some Apple computers); the "Polish programmer's" () layout has become