/ 
Encode-1.20
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/ Encode::Supported

NAME

Encode::Supported -- Supported encodings by Encode

DESCRIPTION

Encoding Names

Encoding names are case insensitive. White space in names is ignored. In addition an encoding may have aliases. Each encoding has one "canonical" name. The "canonical" name is chosen from the names of the encoding by picking the first in the following sequence (with a few exceptions).

  • The name used by the perl community. That includes 'utf8' and 'ascii'. Unlike aliases, canonical names directly reaches the method so such frequently used words like 'utf8' should do without alias lookups.

  • The MIME name as defined in IETF RFCs This includes all "iso-"'s.

  • The name in the IANA registry.

  • The name used by the organization that defined it.

In case de jure canonical names differ from that of the Encode module, they are always aliased if it ever be implemented. So you can safely tell if a given encoding is implemented or not just by passing the canonical name.

Because of all the alias issues, and because in the general case encodings have state, "Encode" uses the encoding object internally once an operation is in progress.

Supported Encodings

As of Perl 5.8.0, at least the following encodings are recognized. Note that unless otherwise specified, they are all case insensitive (via alias) and all occurrance of spaces are replaced with '-'. In other words, "ISO 8859 1" and "iso-8859-1" are identical.

Encodings are categorized and implemented in several different modules but you don't have to use Encode::XX to make them available for most cases. Encode.pm will automatically load those modules in need.

Built-in Encodings

The following encodings are always available.

Canonical	Aliases                      Comments & References
----------------------------------------------------------------
ascii         US-ascii				    [ECMA]
iso-8859-1	latin1					     [ISO]
utf8          UTF-8					 [RFC2279]
UCS-2		ucs2, iso-10646-1, UTF-16LE             [IANA, UC]
UTF-16LE      UCS-2LE                                       [UC]
----------------------------------------------------------------

Encode::Byte -- Extended ASCII

Encode::Byte implements most of single-byte encodings except for Symbols and EBCDIC. The following encodings are based single-byte encoding implemented as extended ASCII. For most cases it uses \x80-\xff (upper half) to map non-ASCII characters.

ISO-8859 and corresponding vendor mappings

Since there are so many, They are presented in table format with Languages and corresponding encoding names by vendors. Note the table is sorted in order of ISO-8859 and the corresponding vendor mappings are slightly different from that of ISO. See http://czyborra.com/charsets/iso8859.html for details.

  Lang/Regions	ISO/Other Std.	DOS	Windows	Macintosh  Others
  ----------------------------------------------------------------
  N. America    (ASCII)		cp437	     AdobeStandardEncoding
				cp863 (DOSCanadaF)
  W.  Europe	(iso-8859-1)	cp850	cp1252	MacRoman  nextstep
							 hp-roman8
				cp860 (DOSPortuguese)
  CE. Europe	iso-8859-2	cp852   cp1250	MacCentralEurRoman
						MacCroatian
						MacRomanian
						MacRumanian
  Latin3(*3)	iso-8859-3	
  Latin4(*4)	iso-8859-4		
  Cyrillics	iso-8859-5 	cp855	cp1251	MacCyrillic
    (Also see next section)	cp866		MacUkrainian
  Arabic	iso-8859-6	cp864	cp1256	MacArabic
				cp1006          MacFarsi
  Greek		iso-8859-7	cp737	cp1253	MacGreek
				cp869 (DOSGreek2)
  Hebrew	iso-8859-8	cp862	cp1255	MacHebrew
  Turkish	iso-8859-9	cp857	cp1254	MacTurkish
  Nordics	iso-8859-10	cp865
				cp861		MacIcelandic
						MacSami
  Thai		iso-8859-11	cp874		MacThai
  (iso-8859-12 is nonexistent. Reserved for Indics?)
  Baltics       iso-8859-13   	cp775		cp1257
  Celtics       iso-8859-14
  Latin9(*15)   iso-8859-15
  Latin10       iso-8859-16
  Vietnamese	viscii			cp1258	MacVietnamese
  ----------------------------------------------------------------

  (*3) Esperanto, Maltese, and Turkish. Turkish is now on 8859-5
  (*4) Baltics.  Now on 8859-10
  (*9) Nicknamed Latin0; Euro sign as well as  French and Finnish
       letters that are missing from 8859-1 are added.

All cp* are also available as ibm-*, ms-*, and windows-* . See also http://czyborra.com/charsets/codepages.html.

Macintosh encodings don't seem to be registered in such entities as IANA. "Canonical" names in Encode are based upon Apple's Tech Note 1150. See http://developer.apple.com/technotes/tn/tn1150.html for details

KOI8 - De Facto Standard for Cyrillic world

Though ISO-8859 does have ISO-8859, KOI8 series is far more popular in the Net. Encode comes with the following KOI charsets. for gory details, See <http://czyborra.com/charsets/cyrillic.html> for details.

----------------------------------------------------------------
koi8-f					
koi8-r cp878						 [RFC1489]
koi8-u						 [RFC2319]
gsm0338 - Hentai Latin 1

GSM0338 is for GSM handsets. Though it shares alpanumerals with ASCII, control character ranges and other parts are mapped very differently, presumablly to store Cyrillics. This one is also covered in Encode::Byte even thought this one does not comply extended ASCII.

The CJK: Chinese, Japanese, Korean (Multibyte)

Note Vietnamese is listed above. Also read "Encoding vs Charset" below. Also note these are implemented in distinct module by languages, due the the size concerns. Please also refer to their respective document pages.

Encode::CN -- Continental China
Standard	DOS/Win	Macintosh	Comment
----------------------------------------------------------------
euc-cn		MacChineseSimp  GB2312 is aliased to this 
(gbk)         cp936			GBK is aliased to to this
gb12345-raw				GB12345 as is
gb2312-raw				GB2312 as is
hz
iso-ir-165
----------------------------------------------------------------
Encode::JP -- Japan
Standard	DOS/Win	Macintosh	Comment/Reference
----------------------------------------------------------------
euc-jp
shiftjis	cp932	macJapanese
7bit-jis	  jis
euc-jp	  ujis
iso-2022-jp				[RFC1468]
iso-2022-jp-1				[RFC2237]
----------------------------------------------------------------
Encode::KR -- Korea
  ----------------------------------------------------------------
  euc-kr		MacKorean                        [RFC1557]
		cp949			ks_c_5601-1987 is an alias
					thereof.
  iso-2022-kr				                 [RFC1557]
  johab                                  [KS X 1001:1998, Annex 3]
  ksc5601-raw				KSC5601 as is
  ----------------------------------------------------------------
Encode::TW -- Taiwan
----------------------------------------------------------------
big5		cp950	MacChineseTrad
big5-hkscs
----------------------------------------------------------------
Encode::HanExtra -- More Chinese via CPAN

Due to size concerns, additional Chinese encodings below are distributed separately on CPAN, under the name Encode::HanExtra.

----------------------------------------------------------------
gb18030
euc-tw
big5plus
----------------------------------------------------------------

Miscellaneous encodings

Encode::EBCDIC

See perlebcdic for details.

----------------------------------------------------------------
cp37
cp500  
cp875  
cp1026  
cp1047  
posix-bc
----------------------------------------------------------------
Encode::Symbols

For symbols and dingbats.

----------------------------------------------------------------
symbol
dingbats
MacDingbats
AdobeZdingbat
AdobeSymbol
----------------------------------------------------------------

Unsupported encodings

The following are not supported as yet. Some because they are rarely usede, some because of technical difficulty. They may be supported by external modules via CPAN in future, however.

ISO-2022-JP-2 [RFC1554]

Not very popular yet. Needs Unicode Database or equivalent to implement encode() (Because it includes JIS X 0208/0212, KSC5601, and GB2312 sumulteniously, which code points in unicode overlap. So you need to lookup the database to determine what character set a given Unicode character should belong).

ISO-2022-CN [RFC1922]

Not very popular. Needs CNS 11643-1 and 2 which are not available in this module. CNS 11643 is supported (via euc-tw) in Encode::HanExtra. Autrijus may add support for this encoding in his module in future

various UP-UX encodings

The following are unsoported due to the lack of mapping data.

'8'  - arabic8, greek8, hebrew8, kana8, thai8, and turkish8
'15' - japanese15, korean15, and  roi15
Cyrillic encoding ISO-IR-111

Anton doubts its usefulness.

ISO-8859-8-1 [Hebrew]

None of the Encode team knows Hebrew enough (ISO-8859-8, cp1255 and MacHebrew are supported because and just because there were mappings available at http://www.unicode.org/). Contribution welcome.

Thai encoding TCVN

Ditto.

Vietnamese encodings VPS

Though Jungshik has reported that mozilla supports this encoding, It was too late for us to add one. In future via a separate module. See http://lxr.mozilla.org/seamonkey/source/intl/uconv/ucvlatin/vps.uf and http://lxr.mozilla.org/seamonkey/source/intl/uconv/ucvlatin/vps.ut if you are interested in helping us.

various Mac encodings

The following are unsoported due to the lack of mapping data.

MacArmenian,  MacBengali,   MacBurmese,   MacEthiopic
MacExtArabic, MacGeorgian,  MacKannada,   MacKhmer
MacLaotian,   MacMalayalam, MacMongolian, MacOriya
MacSinhalese, MacTamil,     MacTelugu,    MacTibetan
MacVietnamese

The rest of which already available are based upon the vendor mappings at http://www.unicode.org/Public/MAPPINGS/VENDORS/APPLE/ .

(Mac) Indic encodings

The maps for the following is available at http://www.unicode.org/ but remains unsupport because those encordigs need algorithmical approach, unsupported by enc2xs

MacDevanagari
MacGurmukhi
MacGujarati

For details, please see Unicode mapping issues and notes: at http://www.unicode.org/Public/MAPPINGS/VENDORS/APPLE/DEVANAGA.TXT .

I believe this issue is prevalent not only for Mac Indics but also in other Indic encodings but those mentions were the only Indic encodings maps that I could find at http://www.unicode.org/ .

Encoding vs. Charset -- terminology

We are used to using the term (character) encoding and character set interchangeably. But just as using the term byte and character is dangerous and should be differenciated when needed, we need to differenciate encoding and character set.

To understand that, it's follow how we make computers grok our character.

  • First we start with which characters to include. We call this collection of characters character repertoire.

  • Then we have to give each character a unique ID so your computer can tell the differnce from 'a' to 'A'. This itemized character repartoire is now a character set.

  • If your computer can grow the character set without further proccessing, you can go ahead use it. This is called a coded character set (CCS) or raw character encoding. ASCII is used this way for most cases.

  • But in many cases especially multi-byte CJK encodings, you have to tweak a little more. Your network connection may not accept any data with the Most Significant Bit set, Your computer may not be able to tell if a given byte is a whole character or just half of it. So you have to encode the character set to use it.

    A character encoding scheme (CES) determines how to encode a given character set, or a set of multiple character sets. 7bit ISO-2022 is an example of CES. You switch between character sets via escape sequence.

Technically, or Mathematically speaking, a character set encoded in such a CES that maps character by character may form a CCS. EUC is such an example. CES of EUC is as follows;

  • Map ASCII unchanged.

  • Map such a character set that consists of 94 or 96 powered by N members by adding 0x80 to each byte.

  • You can also use 0x8e and 0x8f to tell the following sequence of characters belong to yet another character set. each following byte is added by 0x80

By carefully looking at at the encoded byte sequence, you may find the byte sequence conforms a unique number. In that sense EUC is a CCS generated by a CES above from up to four CCS (complicated?). UTF-8 falls into this category. See "UTF-8" in perlunicode to find how UTF-8 maps Unicode to a byte sequence.

You may also find by now why 7bit ISO-2022 cannot conform a CCS. If you look at a byte sequence \x21\x21, you can't tell if it is two !'s or IDEOGRAPHIC SPACE. EUC maps the latter to \xA1\xA1 so you have no trouble between "!!". and " "

Encoding Classification (by Anton Tagunov and Dan Kogai)

This section tries to classify the supported encodings by their applicability for information exchange over the Internet and to choose the most suitable aliases to name them in the context of such communication.

  • To (en|de) code Encodings marked as (*), You need Encode::HanExtra, available from CPAN.

Encoding names

US-ASCII    UTF-8     ISO-8859-*  KOI8-R
Shift_JIS   EUC-JP  ISO-2022-JP ISO-2022-JP-1
EUC-KR      Big5      GB2312

are registered to IANA as preferred MIME names and may probably be used over the Internet.

Shift_JIS has been officialized by JIS X 0208-1997. "Microsoft-related naming mess" gives details.

GB2312 is the IANA name for EUC-CN. See "Microsoft-related naming mess" for details.

GB_2312-80 raw encoding is available as gb2312-raw with Encode. See "Encode::CN -- Continental China" for details.

EUC-CN
KOI8-U        (http://www.faqs.org/rfcs/rfc2319.html)

have not been registered with IANA (as of March 2002) but seem to be supported by major web browsers. IANA name for EUC-CN is GB2312.

KS_C_5601-1987

is heavily misused. See "Microsoft-related naming mess" for details.

KS_C_5601-1987 raw encoding is available as kcs5601-raw with Encode. See "Encode::KR -- Korea" for details.

UTF-16

is a IANA-registered preferred MIME name but probably should be avoided as encoding for web pages due to the lack of browser support.

ISO-IR-165    (http://www.faqs.org/rfcs/rfc1345.html)
GBK
VISCII
GB 12345
GB 18030 (*)  (see links bellow)
EUC-TW   (*)

are totally valid encodings but not registered at IANA. The names under which they are listed here are probably the most widely-known names for these encodings and are recommended names.

BIG5PLUS (*)

is a bit proprietary name.

Microsoft products misuse the following names:

KS_C_5601-1987

Microsoft extension to EUC-KR.

Proper name: CP949.

See http://lists.w3.org/Archives/Public/ietf-charsets/2001AprJun/0033.html for details.

Encode aliases KS_C_5601-1987 to cp949 to reflect this common misusage. Raw KS_C_5601-1987 encoding is available as kcs5601-raw.

See "Encode::KR -- Korea" for details.

GB2312

Microsoft extension to EUC-CN.

Proper names: CP936, GBK.

GB2312 has been registered in the EUC-CN meaning at IANA. This has partially repaired the situation: Microsoft's GB2312 has become a superset of the official GB2312.

Encode aliases GB2312 to euc-cn in full agreement with IANA registration. cp936 is supported separately. Raw GB_2312-80 encoding is available as kcs5601-raw.

See "Encode::CN -- Continental China" for details.

Big5

Microsoft extension to Big5.

Proper name: CP950.

Encode separately supports Big5 and cp950.

Shift_JIS

Microsoft's understanding of Shift_JIS.

JIS has not endorsed the full Microsoft standard however. The official Shift_JIS includes only JIS X 0201 and JIS X 0208 subsets, while Microsoft has always been meaning Shift_JIS to encode a wider character repertoire.

As a historical predecessor Microsoft's variant probably has more rights for the name, albeit it may be objected that Microsoft shouldn't have used JIS as part of the name in the first place.

Unabiguous name: CP932.

Encode separately supports Shift_JIS and cp932.

Glossary

character repertoire

A collection of unique characters. A character set in the most strict sense. At this stage characters are not numberd.

coded character set (CCS)

A character set that is mapped in a way computers can use directly. Many character encodings including EUC falls in this category.

character encoding scheme (CES)

An algorithm to map a character set to a byte sequence. You don't have to be able to tell which character set a given byte sequence belongs. 7-bit ISO-2022 is a CES but it cannot be a CCS. EUC is an example of being both a CCS and CES.

EUC

Extended Unix Character. See ISO-2022

ISO-2022

A CES that was carefully designed to coexist with ASCII. There are 7 bit version and 8 bit version. 8 bit version can conform a CCS. EUC and ISO-8859 are two examples thereof.

UCS

Short for Universal Character Set. When you say just UCS, it means Unicode

UCS-2

ISO/IEC 10646 encoding form: Universal Character Set coded in two octets.

Unicode

A Character Set that aims to include all character character repertoire of the world. Many character sets in various national as well as industorial standards are therefore a subset thereof.

UTF

Short for Unicode Transformation Format. Determinse how to map a unicode character into byte sequnece.

UTF-16

A UTF in 16-bit encoding. Can either be in big endian or little endian. Big endian version is called UTF-16BE and little endian version is UTF-16LE.

See Also

Encode, Encode::Byte, Encode::CN, Encode::JP, Encode::KR, Encode::TW, Encode::EBCDIC, Encode::Symbol

References

ECMA

European Computer Manufacturers Association http://www.ecma.ch

EMCA-035 (eq ISO-2022)

http://www.ecma.ch/ecma1/STAND/ECMA-035.HTM

The very dspecification of ISO-2022 is available from the link above.

IANA

Internet Assigned Numbers Authority http://www.iana.org/

Assigned Charset Names by IANA

http://www.iana.org/assignments/character-sets

Most of the canonical names in Encode derive from this list so you can directly apply the string you have extracted from MIME header of mails and we pages.

ISO

International Organization for Standardization http://www.iso.ch/

RFC

Request For Comment -- need I say more? http://www.rfc.net/

UC

Unicode Consortium http://www.unicode.org/

Unicode Glossary

http://www.unicode.org/glossary/

The glossary of this document is based opon this site.

Other Notable Sites

czyborra.com

<http://czyborra.com/>

Contains a a lot of useful information, especially gory details of ISO vs. vendor mappings.

CJK.inf

http://www.oreilly.com/people/authors/lunde/cjk_inf.html

Somewhat obsolete (last update in 1996), but still useful. Also try

ftp://ftp.oreilly.com/pub/examples/nutshell/cjkv/pdf/GB18030_Summary.pdf

You will find brief info on EUC-CN, GBK and mostly on GB 18030