ISO/IEC 2022

Not to be confused with ISO 20022.

ISO 2022
Language(s)Various.
Standard
ClassificationStateful system of encodings (with stateless pre-configured subsets)
Transforms / EncodesUS-ASCII and, depending on implementation:
Succeeded byISO/IEC 10646 (Unicode)
Other related encoding(s)Stateful subsets:
Pre-configured versions:

ISO/IEC 2022 Information technology—Character code structure and extension techniques, is an ISO/IEC standard in the field of character encoding. It is equivalent to the ECMA standard ECMA-35,[1][2] the ANSI standard ANSI X3.41[3] and the Japanese Industrial Standard JIS X 0202. Originating in 1971, it was most recently revised in 1994.[4]

ISO 2022 specifies a general structure which character encodings can conform to, dedicating particular ranges of bytes (0x00–1F and 0x7F–9F) to be used for non-printing control codes[5] for formatting and in-band instructions (such as line breaks or formatting instructions for text terminals), rather than graphical characters. It also specifies a syntax for escape sequences, multiple-byte sequences beginning with the ESC control code, which can likewise be used for in-band instructions.[6] Specific sets of control codes and escape sequences designed to be used with ISO 2022 include ISO/IEC 6429, portions of which are implemented by ANSI.SYS and terminal emulators.

ISO 2022 itself also defines particular control codes and escape sequences which can be used for switching between different coded character sets (for example, between ASCII and the Japanese JIS X 0208) so as to use multiple in a single document,[7] effectively combining them into a single stateful encoding (a feature less important since the advent of Unicode). It is designed to be usable in both 8-bit environments and 7-bit environments (those where only seven bits are usable in a byte, such as e-mail without 8BITMIME).[8]

  1. ^ ECMA-35 (1994), Brief History
  2. ^ ECMA-35 (1994), p. 51, annex D
  3. ^ Cite error: The named reference marc-escs was invoked but never defined (see the help page).
  4. ^ "ECMA-35: Character code structure and extension techniques (web page)". Ecma International. Archived from the original on 2022-04-25. Retrieved 2022-04-27.
  5. ^ Cite error: The named reference 8.1 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference ch13 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference ch12_14 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference ch11 was invoked but never defined (see the help page).