ISO/IEC 646
ISO/IEC 646 Invariant. Red looped squares (⌘) denote national code points. Other red characters are changed in noteworthy minor modifications. | |
| Standard | ISO/IEC 646, ITU T.50 |
|---|---|
| Classification | 7-bit Basic Latin encoding |
| Preceded by | US-ASCII |
| Succeeded by | ISO/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 Information technology — ISO 7-bit coded character set for information interchange, is an ISO/IEC standard in the field of character encoding. It is equivalent to the ECMA standard ECMA-6 and developed in cooperation with ASCII at least since 1964. The first version of ECMA-6 had been published in 1965, based on work the ECMA's Technical Committee TC1 had carried out since December 1960. The first edition of ISO/IEC 646 was published in 1973, and the most recent, third, edition in 1991.
ISO/IEC 646 specifies a 7-bit character code from which several national standards are derived. It allocates a set of 82 unique graphic characters to 7-bit code points, known as the invariant (INV) or basic character set, including letters of the ISO basic Latin alphabet, digits, and some common English punctuation. It leaves 12 code points to be allocated by conforming national standards for additional letters of Latin-based alphabets or other symbols.
It also defines the International Reference Version (IRV), including a full allocation of 94 graphic characters, to be used when a specific national version is not required. As of the 1991 edition of ISO/IEC 646, the IRV and ASCII are identical. Previous editions differed in only one or two code points.