T.50 (standard)

ITU-T recommendation T.50 specifies the International Reference Alphabet (IRA), formerly International Alphabet No. 5 (IA5), a character encoding. ASCII is the U.S. variant of that character set.

The original version from November 1988 corresponds to ISO 646. The current version is from September 1992.

History
At the beginning was the International Telegraph Alphabet No. 2 (ITA2), a five bits code. IA5 is an improvement based on seven bits bytes.


 * Recommendation V.3 IA5 (1968) Initial version, superseded
 * Recommendation V.3 IA5 (1972) Superseded
 * Recommendation V.3 IA5 (1976-10) Superseded
 * Recommendation V.3 IA5 (1980-11) Superseded
 * Recommendation T.50 IA5 (1984-10) Superseded
 * Recommendation T.50 IA5 (1988-11-25) Superseded
 * Recommendation T.50 IRA (1992-09-18) In force

Use
This standard is referenced by other standards such as RFC 3966. It is also used by some analog modems such as Cisco ones.

This standard is referenced by other standards such as RFC 3939 - Calling Line Identification for Voice Mail Messages.

Character set
The following table shows the IA5 character set. Each character is shown with the hex code of its Unicode equivalent.

{{legend|#DDD|Undefined (showing the ASCII character that is at that location)}} {{legend|#FFD|A character that, in some regions, could be combined with a previous character as a diacritic using the backspace character, which may affect glyph choice.}}

Standardisation

 * Identical standard: ISO/IEC 646:1991 (Twinned)