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Encode::Supported(3pm)		 Perl Programmers Reference Guide	   Encode::Supported(3pm)

       Encode::Supported -- Encodings supported by Encode

       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).

       o   The name used by the Perl community.  That includes 'utf8' and 'ascii'.  Unlike
	   aliases, canonical names directly reach the method so such frequently used words like
	   'utf8' don't need to do alias lookups.

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

       o   The name in the IANA registry.

       o   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 imple-
       mented 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 an 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 oth-
       erwise specified, they are all case insensitive (via alias) and all occurrence 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 on demand.

       Built-in Encodings

       The following encodings are always available.

	 Canonical     Aliases			    Comments & References
	 ascii	       US-ascii ISO-646-US			   [ECMA]
	 ascii-ctrl					 Special Encoding
	 iso-8859-1    latin1					    [ISO]
	 null						 Special Encoding
	 utf8	       UTF-8					[RFC2279]

       null and ascii-ctrl are special.  "null" fails for all character so when you set fallback
       mode to PERLQQ, HTMLCREF or XMLCREF, ALL CHARACTERS will fall back to character refer-
       ences.  Ditto for "ascii-ctrl" except for control characters.  For fallback modes, see

       Encode::Unicode -- other Unicode encodings

       Unicode coding schemes other than native utf8 are supported by Encode::Unicode, which will
       be autoloaded on demand.

	 UCS-2BE       UCS-2, iso-10646-1		       [IANA, UC]
	 UCS-2LE						     [UC]
	 UTF-16 						     [UC]
	 UTF-16BE						     [UC]
	 UTF-16LE						     [UC]
	 UTF-32 						     [UC]
	 UTF-32BE      UCS-4					     [UC]
	 UTF-32LE						     [UC]

       To find how (UCS-2|UTF-(16|32))(LE|BE)? differ from one another, see Encode::Unicode.

       Encode::Byte -- Extended ASCII

       Encode::Byte implements most single-byte encodings except for Symbols and EBCDIC. The fol-
       lowing encodings are based on single-byte encodings implemented as extended ASCII.  Most
       of them map \x80-\xff (upper half) to non-ASCII characters.

       ISO-8859 and corresponding vendor mappings
	   Since there are so many, they are presented in table format with languages and corre-
	   sponding encoding names by vendors.	Note that 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
					   cp860 (DOSPortuguese)
	     Cntrl. Europe iso-8859-2	   cp852   cp1250  MacCentralEurRoman
	     Latin3[1]	   iso-8859-3
	     Latin4[2]	   iso-8859-4
	     Cyrillics	   iso-8859-5	   cp855   cp1251  MacCyrillic
	       (See also 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
	     Thai	   iso-8859-11[3]  cp874	   MacThai
	     (iso-8859-12 is nonexistent. Reserved for Indics?)
	     Baltics	   iso-8859-13	   cp775	   cp1257
	     Celtics	   iso-8859-14
	     Latin9 [4]    iso-8859-15
	     Latin10	   iso-8859-16
	     Vietnamese    viscii		   cp1258  MacVietnamese

	     [1] Esperanto, Maltese, and Turkish. Turkish is now on 8859-9.
	     [2] Baltics.  Now on 8859-10, except for Latvian.
	     [3] TIS 620 +  Non-Breaking Space (0xA0 / U+00A0)
	     [4] Nicknamed Latin0; the Euro sign as well as French and Finnish
		 letters that are missing from 8859-1 were added.

	   All cp* are also available as ibm-*, ms-*, and windows-* .  See also <http://czy-

	   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://devel-
	   oper.apple.com/technotes/tn/tn1150.html> for details.

       KOI8 - De Facto Standard for the Cyrillic world
	   Though ISO-8859 does have ISO-8859-5, the KOI8 series is far more popular in the Net.
	   Encode comes with the following KOI charsets.  For gory details, see <http://czy-

	     koi8-r cp878					    [RFC1489]
	     koi8-u						    [RFC2319]

       gsm0338 - Hentai Latin 1
	   GSM0338 is for GSM handsets. Though it shares alphanumerals with ASCII, control char-
	   acter ranges and other parts are mapped very differently, presumably to store Greek
	   and Cyrillic alphabets.  This is also covered in Encode::Byte even though it is not an
	   "extended ASCII" encoding.

       CJK: Chinese, Japanese, Korean (Multibyte)

       Note that Vietnamese is listed above.  Also read "Encoding vs Charset" below.  Also note
       that these are implemented in distinct modules by countries, due to the size concerns
       (simplified Chinese is mapped to 'CN', continental China, while traditional Chinese is
       mapped to 'TW', Taiwan).  Please refer to their respective documentation pages.

       Encode::CN -- Continental China
	     Standard	   DOS/Win Macintosh		    Comment/Reference
	     euc-cn [1] 	   MacChineseSimp
	     (gbk)	   cp936 [2]
	     gb12345-raw		      { GB12345 without CES }
	     gb2312-raw 		      { GB2312	without CES }

	     [1] GB2312 is aliased to this.  See L<Microsoft-related naming mess>
	     [2] gbk is aliased to this.  See L<Microsoft-related naming mess>

       Encode::JP -- Japan
	     Standard	   DOS/Win Macintosh		    Comment/Reference
	     shiftjis	   cp932   macJapanese
	     iso-2022-jp					    [RFC1468]
	     iso-2022-jp-1					    [RFC2237]
	     jis0201-raw  { JIS X 0201 (roman + halfwidth kana) without CES }
	     jis0208-raw  { JIS X 0208 (Kanji + fullwidth kana) without CES }
	     jis0212-raw  { JIS X 0212 (Extended Kanji) 	without CES }

       Encode::KR -- Korea
	     Standard	   DOS/Win Macintosh		    Comment/Reference
	     euc-kr		   MacKorean			    [RFC1557]
			   cp949 [1]
	     iso-2022-kr					    [RFC1557]
	     johab				    [KS X 1001:1998, Annex 3]
	     ksc5601-raw			      { KSC5601 without CES }

	     [1] ks_c_5601-1987, (x-)?windows-949, and uhc are aliased to this.
	     See below.

       Encode::TW -- Taiwan
	     Standard	   DOS/Win Macintosh		    Comment/Reference
	     big5-eten	   cp950   MacChineseTrad {big5 aliased to big5-eten}

       Encode::HanExtra -- More Chinese via CPAN
	   Due to the size concerns, additional Chinese encodings below are distributed sepa-
	   rately on CPAN, under the name Encode::HanExtra.

	     Standard	   DOS/Win Macintosh		    Comment/Reference
	     big5ext				       CMEX's Big5e Extension
	     big5plus				       CMEX's Big5+ Extension
	     cccii	   Chinese Character Code for Information Interchange
	     euc-tw				EUC (Extended Unix Character)
	     gb18030			      GBK with Traditional Characters

       Encode::JIS2K -- JIS X 0213 encodings via CPAN
	   Due to size concerns, additional Japanese encodings below are distributed separately
	   on CPAN, under the name Encode::JIS2K.

	     Standard	   DOS/Win Macintosh		    Comment/Reference

       Miscellaneous encodings

	   See perlebcdic for details.


	   For symbols	and dingbats.


	   Strictly speaking, MIME header encoding documented in RFC 2047 is more of encapsula-
	   tion than encoding.	However, their support in modern world is imperative so they are

	     MIME-Header					    [RFC2047]
	     MIME-B						    [RFC2047]
	     MIME-Q						    [RFC2047]

	   This one is not a name of encoding but a utility that lets you pick up the most appro-
	   priate encoding for a data out of given suspects.  See Encode::Guess for details.

Unsupported encodings
       The following encodings are not supported as yet; some because they are rarely used, some
       because of technical difficulties.  They may be supported by external modules via CPAN in
       the 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 simultaneously, whose code
	   points in Unicode overlap.  So you need to lookup the database to determine to 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 Tang may add sup-
	   port for this encoding in his module in future.

       Various HP-UX encodings
	   The following are unsupported 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 Tagunov doubts its usefulness.

       ISO-8859-8-1 [Hebrew]
	   None of the Encode team knows Hebrew enough (ISO-8859-8, cp1255 and MacHebrew are sup-
	   ported because and just because there were mappings available at <http://www.uni-
	   code.org/>).  Contributions welcome.

       ISIRI 3342, Iran System, ISIRI 2900 [Farsi]

       Thai encoding TCVN

       Vietnamese encodings VPS
	   Though Jungshik Shin has reported that Mozilla supports this encoding, it was too late
	   before 5.8.0 for us to add it.  In the future, it may be available via a separate mod-
	   ule.  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 inter-
	   ested in helping us.

       Various Mac encodings
	   The following are unsupported due to the lack of mapping data.

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

	   The rest which are 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 are available at <http://www.unicode.org/> but remain
	   unsupport because those encodings need algorithmical approach, currently unsupported
	   by enc2xs:


	   For details, please see "Unicode mapping issues and notes:" at <http://www.uni-

	   I believe this issue is prevalent not only for Mac Indics but also in other Indic
	   encodings, but the above 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 confusing the terms byte and character is dangerous and the terms should be dif-
       ferentiated when needed, we need to differentiate encoding and character set.

       To understand that, here is a description of how we make computers grok our characters.

       o   First we start with which characters to include.  We call this collection of charac-
	   ters character repertoire.

       o   Then we have to give each character a unique ID so your computer can tell the differ-
	   ence between 'a' and 'A'.  This itemized character repertoire is now a character set.

       o   If your computer can grow the character set without further processing, you can go
	   ahead and use it.  This is called a coded character set (CCS) or raw character encod-
	   ing.  ASCII is used this way for most cases.

       o   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, and 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 a CES.  You switch
	   between character sets via escape sequences.

       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.	The CES of EUC is as fol-

       o   Map ASCII unchanged.

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

       o   You can also use 0x8e and 0x8f to indicate that the following sequence of characters
	   belongs to yet another character set.  To each following byte is added the value 0x80.

       By carefully looking at the encoded byte sequence, you can find that 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 out how UTF-8 maps Unicode to a byte sequence.

       You may also have found out by now why 7bit ISO-2022 cannot comprise 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 differentiating between "!!". and " ".

Encoding Classification (by Anton Tagunov and Dan Kogai)
       This section tries to classify the supported encodings by their applicability for informa-
       tion exchange over the Internet and to choose the most suitable aliases to name them in
       the context of such communication.

       o   To (en|de)code encodings marked by "(**)", you need "Encode::HanExtra", available from

       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 with IANA as preferred MIME names and may 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 for

	 KOI8-U        [RFC2319]

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


       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
       for details.

	 UTF-16 UTF-16BE UTF-16LE

       are IANA-registered "charset"s. See [RFC 2781] for details.  Jungshik Shin reports that
       UTF-16 with a BOM is well accepted by MS IE 5/6 and NS 4/6. Beware however that

       o   "UTF-16" support in any software you're going to be using/interoperating with has
	   probably been less tested then "UTF-8" support

       o   "UTF-8" coded data seamlessly passes traditional command piping ("cat", "more", etc.)
	   while "UTF-16" coded data is likely to cause confusion (with its zero bytes, for exam-

       o   it is beyond the power of words to describe the way HTML browsers encode non-"ASCII"
	   form data. To get a general impression, visit
	   <http://ppewww.ph.gla.ac.uk/~flavell/charset/form-i18n.html>.  While encoding of form
	   data has stabilized for "UTF-8" encoded pages (at least IE 5/6, NS 6, and Opera 6
	   behave consistently), be sure to expect fun (and cross-browser discrepancies) with
	   "UTF-16" encoded pages!

       The rule of thumb is to use "UTF-8" unless you know what you're doing and unless you
       really benefit from using "UTF-16".

	 ISO-IR-165    [RFC1345]
	 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 recom-
       mended names.

	 BIG5PLUS (**)

       is a proprietary name.

       Microsoft-related naming mess

       Microsoft products misuse the following names:

	   Microsoft extension to "EUC-KR".

	   Proper names: "CP949", "UHC", "x-windows-949" (as used by Mozilla).

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

	   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 for details.

	   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

	   Encode aliases "GB2312" to "euc-cn" in full agreement with IANA registration. "cp936"
	   is supported separately.  Raw "GB_2312-80" encoding is available as "gb2312-raw".

	   See Encode::CN for details.

	   Microsoft extension to "Big5".

	   Proper name: "CP950".

	   Encode separately supports "Big5" and "cp950".

	   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 character sets, while Microsoft has always
	   used "Shift_JIS" to encode a wider character repertoire. See "IANA" registration for

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

	   Unambiguous name: "CP932". "IANA" name (not used?): "Windows-31J".

	   Encode separately supports "Shift_JIS" and "cp932".

       character repertoire
	   A collection of unique characters.  A character set in the strictest sense. At this
	   stage, characters are not numbered.

       coded character set (CCS)
	   A character set that is mapped in a way computers can use directly.	Many character
	   encodings, including EUC, fall 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.

       charset (in MIME context)
	   has long been used in the meaning of "encoding", CES.

	   While the word combination "character set" has lost this meaning in MIME context since
	   [RFC 2130], the "charset" abbreviation has retained it. This is how [RFC 2277] and
	   [RFC 2278] bless "charset":

	    This document uses the term "charset" to mean a set of rules for
	    mapping from a sequence of octets to a sequence of characters, such
	    as the combination of a coded character set and a character encoding
	    scheme; this is also what is used as an identifier in MIME "charset="
	    parameters, and registered in the IANA charset registry ...  (Note
	    that this is NOT a term used by other standards bodies, such as ISO).
	    [RFC 2277]

       EUC Extended Unix Character.  See ISO-2022.

	   A CES that was carefully designed to coexist with ASCII.  There are a 7 bit version
	   and an 8 bit version.

	   The 7 bit version switches character set via escape sequence so it cannot form a CCS.
	   Since this is more difficult to handle in programs than the 8 bit version, the 7 bit
	   version is not very popular except for iso-2022-jp, the de facto standard CES for

	   The 8 bit version can form a CCS.  EUC and ISO-8859 are two examples thereof.  Pre-5.6
	   perl could use them as string literals.

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

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

	   A character set that aims to include all character repertoires of the world.  Many
	   character sets in various national as well as industrial standards have become, in a
	   way, just subsets of Unicode.

       UTF Short for Unicode Transformation Format.  Determines how to map a Unicode character
	   into a byte sequence.

	   A UTF in 16-bit encoding.  Can either be in big endian or little endian.  The big
	   endian version is called UTF-16BE (equal to UCS-2 + surrogate support) and the little
	   endian version is called UTF-16LE.

See Also
       Encode, Encode::Byte, Encode::CN, Encode::JP, Encode::KR, Encode::TW, Encode::EBCDIC,
       Encode::Symbol Encode::MIME::Header, Encode::Guess

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

	   ECMA-035 (eq "ISO-2022")

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

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

	   Assigned Charset Names by IANA

	       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 web pages.

       ISO International Organization for Standardization <http://www.iso.ch/>

       RFC Request For Comments -- need I say more?  <http://www.rfc-editor.org/>,
	   <http://www.rfc.net/>, <http://www.faqs.org/rfcs/>

       UC  Unicode Consortium <http://www.unicode.org/>

	   Unicode Glossary

	       The glossary of this document is based upon this site.

       Other Notable Sites


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


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


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

       Jungshik Shin's Hangul FAQ

	   And especially its subject 8.


	   A comprehensive overview of the Korean ("KS *") standards.

       debian.org: "Introduction to i18n"
	   A brief description for most of the mentioned CJK encodings is contained in

       Offline sources

       "CJKV Information Processing" by Ken Lunde
	   CJKV Information Processing 1999 O'Reilly & Associates, ISBN : 1-56592-224-7

	   The modern successor of "CJK.inf".

	   Features a comprehensive coverage of CJKV character sets and encodings along with many
	   other issues faced by anyone trying to better support CJKV languages/scripts in all
	   the areas of information processing.

	   To purchase this book, visit <http://www.oreilly.com/catalog/cjkvinfo/> or your
	   favourite bookstore.

perl v5.8.0				    2002-06-01			   Encode::Supported(3pm)

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