escape sequence
(Or "escape code") A series of characters starting with the escape character (ASCII 27). Escape sequences are often used to control display devices such as VDUs. An escape sequence might change the colour of subsequent text, reassign keys on the keyboard, change printer settings or reposition the cursor. The escape sequences of the DEC vt100 video terminal have become a de facto standard for this purpose.
The term is also used for any sequence of characters that temporarily suspends normal processing of a stream of characters to perform some special function. For example, the Hayes modem uses the sequence "+++" to escape to command mode in which characters are interpreted as commands to the modem itself rather than as data to pass through.