Editing Control character (section)

===Printing and display control===
Printing control characters were first used to control the physical mechanism of printers, the earliest output device.  An early example of this idea was the use of [[Baudot code#Details|Figures (FIGS)]] and [[Baudot code#Details|Letters (LTRS)]] in [[Baudot code]] to shift between two code pages. A later, but still early, example was the [[Out-of-band data|out-of-band]] [[ASA carriage control characters]].  Later, control characters were integrated into the stream of data to be printed.
The carriage return character (CR), when sent to such a device, causes it to put the character at the edge of the paper at which writing begins (it may, or may not, also move the printing position to the next line).
The line feed character (LF/NL) causes the device to put the printing position on the next line. It may (or may not), depending on the device and its configuration, also move the printing position to the start of the next line (which would be the leftmost position for [[left-to-right]] scripts, such as the alphabets used for Western languages, and the rightmost position for [[right-to-left]] scripts such as the Hebrew and Arabic alphabets).
The vertical and horizontal tab characters (VT and HT/TAB) cause the output device to move the printing position to the next tab stop in the direction of reading.
The form feed character (FF/NP) starts a new sheet of paper, and may or may not move to the start of the first line.
The backspace character (BS) moves the printing position one character space backwards. On printers, including [[Computer terminal#Hard-copy terminals|hard-copy terminals]], this is most often used so the printer can overprint characters to make other, not normally available, characters. On [[Computer terminal#VDUs|video terminals]] and other electronic output devices, there are often software (or hardware) configuration choices that allow a destructive backspace (e.g., a BS, SP, BS sequence), which erases, or a non-destructive one, which does not.
The shift in and shift out characters (SI and SO) selected alternate character sets, fonts, underlining, or other printing modes. Escape sequences were often used to do the same thing.

With the advent of [[computer terminal]]s that did not physically print on paper and so offered more flexibility regarding screen placement, erasure, and so forth, printing control codes were adapted. Form feeds, for example, usually cleared the screen, there being no new paper page to move to. More complex escape sequences were developed to take advantage of the flexibility of the new terminals, and indeed of newer printers. The concept of a control character had always been somewhat limiting, and was extremely so when used with new, much more flexible, hardware. Control sequences (sometimes implemented as escape sequences) could match the new flexibility and power and became the standard method. However, there were, and remain, a large variety of standard sequences to choose from.