ISO/IEC 646

For the iso646.h header, see C alternative tokens.

ISO/IEC 646 encoding family
ISO/IEC 646 Invariant. Red looped squares (⌘) denote national code points. Other red characters are changed in noteworthy minor modifications.
StandardISO/IEC 646, ITU T.50
Classification7-bit Basic Latin encoding
Preceded byUS-ASCII
Succeeded byISO/IEC 8859, ISO/IEC 10646
Other related encoding(s)DEC NRCS, World System Teletext
Adaptations to other alphabets:
ELOT 927, Symbol, KOI-7, SRPSCII and MAKSCII, ASMO 449, SI 960

ISO/IEC 646 is a set of ISO/IEC standards, described as Information technology — ISO 7-bit coded character set for information interchange, and developed in cooperation with ASCII at least since 1964.[1][2] Since its first edition in 1967[3] it has specified a 7-bit character code from which several national standards are derived.

ISO/IEC 646 was also ratified by ECMA as ECMA-6. The first version of ECMA-6 had been published in 1965,[4] based on work the ECMA's Technical Committee TC1 had carried out since December 1960.[4]

Characters in the ISO/IEC 646 Basic Character Set are invariant characters.[5] Since that portion of ISO/IEC 646, that is the invariant character set shared by all countries, specified only those letters used in the ISO basic Latin alphabet, countries using additional letters needed to create national variants of ISO/IEC 646 to be able to use their native scripts. Since transmission and storage of 8-bit codes was not standard at the time, the national characters had to be made to fit within the constraints of 7 bits, meaning that some characters that appear in ASCII do not appear in other national variants of ISO/IEC 646.

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  2. ^ Cite error: The named reference ISO_1964 was invoked but never defined (see the help page).
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  4. ^ a b Cite error: The named reference ECMA-6_1985 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Bodfish_2013 was invoked but never defined (see the help page).