Tech Info Pages - Character Sets

This page summarises what at face value seems a remarkably simple concept - character representation. Turns out its more like a nightmare. The column marked relationship tries to define the relationships between the various standards.

Name	Standard	Aliases	Description	Relationship
ASCII	ANSI X3.4-1986 ISO 646 ITU-T T.50	US-ASCII IA5 IRA5 ISO 646	ASCII is encoded as an 8 bit field but only uses the 7 bits 00 to 7F (0 to 127 decimal). Almost all other character codes contain ASCII as a base. Various national definitions exist which typically have only two printable differences.	ASCII is the same as IA5 or more properly now International Reference Alphabet No. 5 (IRA5) and previously International Alphabet No. 5 (defined in ITU-T T.50) and ISO 646. It also forms the first 128 values in ISO 8859-1 (Latin-1), Unicode and ISO 10646 (UCS).
IA5	ITU-T T.50	IRA5 ASCII ISO 646	International Alphabet No. 5 (ISO 646) now renamed International Reference Alphabet No. 5 (IRA5).
IRA5	ITU-T T.50	IA5 ISO 646 ASCII	International Reference Alphabet No. 5 (IRA5) (was International Alphabet No. 5 - IA5) and is the ITU equivalent of US-ASCII and ISO 646. IRA5 is encoded as an 8 bit field but only uses the 7 bits 00 to 7F (0 to 127 decimal). Almost all other character codes contain IRA5 as a base.	IRA5 is the same as ISO 646 and ASCII. It also forms the first 128 values in ISO 8859-1 (Latin-1), Unicode and ISO 10646 (UCS).
ISO 646	ISO 646	IA5 IRA5 ASCII	ISO 646 is encoded as an 8 bit field but only uses the 7 bits 00 to 7F (0 to 127 decimal). Almost all other character codes contain ISO 646 as a base.	ISO 646 is the same as IRA5 (IA5) and ASCII. It also forms the first 128 values in ISO 8859-1 (Latin-1), Unicode and ISO 10646 (UCS).
ISO 8859-1	ISO 8859-1	Latin-1	ISO 8859-1 is part of a large family (ISO 8859-1 to 8859-16) is encoded as an 8 bit field and uses all 8 bits 00 to FF (0 to 255 decimal).	It forms the first 128 values in IRA5, ISO 646, US-ASCII, ISO 8559-15 (Latin-1), Unicode and ISO 10646 (UCS).
ISO 8859-15	ISO 8859-15	Latin-9	ISO 8859-15 is part of a large family (ISO 8859-1 to 8859-16) is encoded as an 8 bit field and uses all 8 bits 00 to FF (0 to 255 decimal). It differs from 8859-1 by 8 changes including the euro symbol.	It forms the first 128 values in IRA5, ISO 646, US-ASCII, ISO 8559-1 (Latin-9), Unicode and ISO 10646 (UCS).
ISO 10646	ISO 10646	UCS	ISO 10646 (Universal Character Set) is designed to be the replacement for all previous character sets by providing a single family of standards for the encoding of all possible characters and symbols in all written languages. It has two implementations UCS-2 (a 16 bit encoding) and UCS-4 (a 32 bit encoding).	The first 128 values in ISO 10646 are the same as ASCII, IA5, IRA5 and ISO 646, 8859-1 and 8859-15. Unicode from version 1.1 is th same as ISO 646.
Unicode	Unicode Consortium	-	Unicode (currently version 3.0).	From version 1.1 is fully compatible with ISO 10646.
CP1252	RFC RFC 2781	-	Microsoft's version of ISO 8859-1. There are 27 differences from 8859-1 (it includes the euro) - all in range x80 - x9F.	The first 128 values are the same as those of IRA5, ISO 646, US-ASCII ISO 8559-1 (Latin-1) & -15 (Latin-9), Unicode and ISO 10646 (UCS).
Transformations
These values define how the underlying codeset of Unicode/ISO 10646 are sent over the wire. They are not charsets.
UTF-7	RFC 2152	-	UCS Transformation Format-7. Defines how ISO 10646 (UCS) is transformed for non-MIME email data communications. May use from 1 to 9 octets for a single ISO 10646/Unicode character.
UTF-8	RFC 3629	UTF-2 FSS-UTF	UCS Transformation Format-8. Defines how ISO 10646 (UCS) is transformed for MIME enabled data communications. May use from 1 to 7 octets for a single ISO 10646/Unicode character.
UTF-16	-	-	UCS Transformation Format-16. Defines how ISO 10646 (UCS) is transformed for data communications. May use 1 or 2 octets for a single ISO 10646/Unicode character and thus reduces any UCS-4 to a UCS-2 format before encoding.

ISO 8859 Family

ISO 8859-1   Latin alphabet No. 1     West European
ISO 8859-2   Latin alphabet No. 2     Central and East European
ISO 8859-3   Latin alphabet No. 3     South European, Maltese & Esperanto
ISO 8859-4   Latin alphabet No. 4     North European
ISO 8859-5   Latin/Cyrillic alphabet  Slavic languages
ISO 8859-6   Latin/Arabic alphabet    Arabic
ISO 8859-7   Latin/Greek alphabet     modern Greek
ISO 8859-8   Latin/Hebrew alphabet    Hebrew and Yiddish
ISO 8859-9   Latin alphabet No. 5     Turkish
ISO 8859-10  Latin alphabet No. 6     Nordic (Sámi, Inuit, Icelandic)
ISO 8859-11  Latin/Thai alphabet      Thai
ISO 8859-12  not been defined)
ISO 8859-13  Latin alphabet No. 7     Baltic Rim
ISO 8859-14  Latin alphabet No. 8     Celtic
ISO 8859-15  Latin alphabet No. 9     adds euro to -1 (8 changes)
ISO 8859-16  Latin alphabet No. 10    South-Eastern Europe

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