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
Keyboard layout 10 includes its own implementation of a mnemonic QWERTY-based input method for Russian, which does not fully rely on assigning a key to every Russian letter, but uses the sh, sc, ch, ya (ja), yu (ju), ye (je), yo (jo) combinations to input ш, щ, ч, я, ю, э, and ё respectively. Virtual (on-screen) Russian keyboards allow entering Cyrillic directly in a browser without activating the system layout. This virtual keyboard offers YaZhERT (яжерт) variant. Another virtual keyboard supports both traditional ("MS Windows" and Typewriter) and some phonetic keyboard layouts, including AATSEEL "Student", Mac OS X Phonetic Russian layout and