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
editAt the beginning was the International Telegraph Alphabet No. 2 (ITA2), a five-bit code. IA5 is an improvement, based on seven-bit bytes.
- Recommendation V.3 IA5 (1968): Initial version, superseded[1][2]
- Recommendation V.3 IA5 (1972): Superseded[1][2]
- Recommendation V.3 IA5 (1976-10): Superseded
- Recommendation V.3 IA5 (1980-11): Superseded
- Recommendation T.50 IA5 (1984-10): Superseded[2]
- Recommendation T.50 IA5 (1988-11-25): Superseded[1][2]
- Recommendation T.50 IRA (1992-09-18): In force[1][3]
Use
editThe IA5STRING string type in ASN.1 is restricted to characters in IA5.[4] This standard is referenced by other standards such as RFC 3939 ("Calling Line Identification for Voice Mail Messages"). It is also used by some analog modems such as Cisco ones.[5]
Character set
editThe following table shows the IA5 character set. Each character is shown with the code point of its Unicode equivalent.
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | A | B | C | D | E | F | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0x | NUL | SOH | STX | ETX | EOT | ENQ | ACK | BEL | BS | HT | LF | VT | FF | CR | SO | SI |
| 1x | DLE | DC1 | DC2 | DC3 | DC4 | NAK | SYN | ETB | CAN | EM | SUB | ESC | FS | GS | RS | US |
| 2x | SP | ! | " | # | $ | % | & | ' | ( | ) | * | + | , | - | . | / |
| 3x | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | : | ; | < | = | > | ? |
| 4x | @ | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O |
| 5x | P | Q | R | S | T | U | V | W | X | Y | Z | [ | \ | ] | ^ | _ |
| 6x | ` | a | b | c | d | e | f | g | h | i | j | k | l | m | n | o |
| 7x | p | q | r | s | t | u | v | w | x | y | z | { | | | } | ~ | DEL |
Standardisation
edit- Identical standard: ISO/IEC 646:1991 (Twinned)
See also
edit- ITU T.51
- PrintableString, a subset of IA5String
References
edit- ^ a b c d Salste, Tuomas (January 2016). "7-bit character sets: Revisions of ASCII". Aivosto Oy. urn:nbn:fi-fe201201011004. Archived from the original on 2016-06-13. Retrieved 2016-06-13.
- ^ a b c d International Alphabet No. 5 - Recommendation T.50, International Telecommunication Union (ITU) - The International Telegraph and Telephone Consultative Committee (CCITT) - Series T: Terminal Equipment and Protocols for Telematic Services, 1993-04-16 [1988-11-25], E 33116, archived from the original on 2017-03-19, retrieved 2017-03-18
- ^ International Reference Alphabet (IRA) - Information Technology - 7-bit Coded Character Set For Information Interchange - Recommendation T.50, International Telecommunication Union (ITU) - The International Telegraph and Telephone Consultative Committee (CCITT) - Terminal Equipment and Protocols for Telematic Services, 1993-04-16 [1992-09-18], E 3177, archived from the original on 2014-12-19, retrieved 2017-03-18
- ^ Dubuisson, Olivier (2000). ASN.1 Communication Between Heterogeneous Systems. Morgan Kaufmann. p. 177. ISBN 978-0-12-633361-9. Retrieved 2026-02-21.
- ^ "AT Command Set and Register Summary for NM-8AM-V2, NM-16AM-V2, WIC-1AM, and WIC-2AM Analog Modem WAN Interface Cards - 2: Syntax and Procedures [Cisco 3600 Series Multiservice Platforms] - Cisco Systems". Cisco.com. Archived from the original on 2011-09-07. Retrieved 2012-10-03.
