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  • Recommendation V.3 IA5 (1968) Initial version, superseded[1][2]
  • Recommendation V.3 IA5 (1972) Superseded[1][2]
  • Recommendation V.3 IA5 (1976-10) Superseded
  • Recommendation V.3 IA5 (1980-11) Superseded
  • Recommendation T.50 IA5 (1984-10) Superseded[2]
  • Recommendation T.50 IA5 (1988-11-25) Superseded[1][2]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

This standard is referenced by other standards such as RFC 3966. It is also used by some analog modems such as Cisco ones.[4]

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.

IA5 character set
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
  Undefined (showing the ASCII character that is at that location)
  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)

See also

References
  1. 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.
  2. 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
  3. 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
  4. "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.
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