Caret notation

Caret notation is a notation for unprintable control characters in ASCII encoding. The notation consists of a caret (^) followed by a capital letter; this digraph stands for the ASCII code that has the numerical value equivalent to the letter's numerical value. For example, ^D represents the end-of-transmission character (abbrevated EOT), which cannot ordinarily be shown on the screen. The letter is D, because it is the 4th letter in the alphabet and EOT has the value 4 in the ASCII encoding. The null character (NUL) is represented as ^@ (@ is the ASCII character before A).

For a complete list of caret notation, see C0 and C1 control codes.

Many computer systems allow you to enter a control character by holding down Ctrl and pressing the letter used in the caret notation. This is practical, because many control characters (e.g. EOT) can not be entered directly from a keyboard. Although there are many ways to represent control characters, this correspondence between notation and typing makes the caret notation suitable for many applications.

Caret notation is used in many programs, particularly Unix-viewers such as more and less.