3 Encode::Supported -- Encodings supported by Encode
9 Encoding names are case insensitive. White space in names
10 is ignored. In addition, an encoding may have aliases.
11 Each encoding has one "canonical" name. The "canonical"
12 name is chosen from the names of the encoding by picking
13 the first in the following sequence (with a few exceptions).
19 The name used by the Perl community. That includes 'utf8' and 'ascii'.
20 Unlike aliases, canonical names directly reach the method so such
21 frequently used words like 'utf8' don't need to do alias lookups.
25 The MIME name as defined in IETF RFCs. This includes all "iso-"s.
29 The name in the IANA registry.
33 The name used by the organization that defined it.
37 In case I<de jure> canonical names differ from that of the Encode
38 module, they are always aliased if it ever be implemented. So you can
39 safely tell if a given encoding is implemented or not just by passing
42 Because of all the alias issues, and because in the general case
43 encodings have state, "Encode" uses an encoding object internally
44 once an operation is in progress.
46 =head1 Supported Encodings
48 As of Perl 5.8.0, at least the following encodings are recognized.
49 Note that unless otherwise specified, they are all case insensitive
50 (via alias) and all occurrence of spaces are replaced with '-'.
51 In other words, "ISO 8859 1" and "iso-8859-1" are identical.
53 Encodings are categorized and implemented in several different modules
54 but you don't have to C<use Encode::XX> to make them available for
55 most cases. Encode.pm will automatically load those modules on demand.
57 =head2 Built-in Encodings
59 The following encodings are always available.
61 Canonical Aliases Comments & References
62 ----------------------------------------------------------------
64 ascii-ctrl Special Encoding
65 iso-8859-1 latin1 [ISO]
68 ----------------------------------------------------------------
70 I<null> and I<ascii-ctrl> are special. "null" fails for all character
71 so when you set fallback mode to PERLQQ, HTMLCREF or XMLCREF, ALL
72 CHARACTERS will fall back to character references. Ditto for
73 "ascii-ctrl" except for control characters. For fallback modes, see
76 =head2 Encode::Unicode -- other Unicode encodings
78 Unicode coding schemes other than native utf8 are supported by
79 Encode::Unicode, which will be autoloaded on demand.
81 ----------------------------------------------------------------
82 UCS-2BE UCS-2, iso-10646-1 [IANA, UC]
90 ----------------------------------------------------------------
92 To find how (UCS-2|UTF-(16|32))(LE|BE)? differ from one another,
93 see L<Encode::Unicode>.
95 =head2 Encode::Byte -- Extended ASCII
97 Encode::Byte implements most single-byte encodings except for
98 Symbols and EBCDIC. The following encodings are based on single-byte
99 encodings implemented as extended ASCII. Most of them map
100 \x80-\xff (upper half) to non-ASCII characters.
104 =item ISO-8859 and corresponding vendor mappings
106 Since there are so many, they are presented in table format with
107 languages and corresponding encoding names by vendors. Note that
108 the table is sorted in order of ISO-8859 and the corresponding vendor
109 mappings are slightly different from that of ISO. See
110 L<http://czyborra.com/charsets/iso8859.html> for details.
112 Lang/Regions ISO/Other Std. DOS Windows Macintosh Others
113 ----------------------------------------------------------------
114 N. America (ASCII) cp437 AdobeStandardEncoding
116 W. Europe iso-8859-1 cp850 cp1252 MacRoman nextstep
118 cp860 (DOSPortuguese)
119 Cntrl. Europe iso-8859-2 cp852 cp1250 MacCentralEurRoman
123 Latin3 [1] iso-8859-3
124 Latin4 [2] iso-8859-4
125 Cyrillics iso-8859-5 cp855 cp1251 MacCyrillic
126 (See also next section) cp866 MacUkrainian
127 Arabic iso-8859-6 cp864 cp1256 MacArabic
129 Greek iso-8859-7 cp737 cp1253 MacGreek
131 Hebrew iso-8859-8 cp862 cp1255 MacHebrew
132 Turkish iso-8859-9 cp857 cp1254 MacTurkish
133 Nordics iso-8859-10 cp865
136 Thai iso-8859-11 [3] cp874 MacThai
137 (iso-8859-12 is nonexistent. Reserved for Indics?)
138 Baltics iso-8859-13 cp775 cp1257
140 Latin9 [4] iso-8859-15
142 Vietnamese viscii cp1258 MacVietnamese
143 ----------------------------------------------------------------
145 [1] Esperanto, Maltese, and Turkish. Turkish is now on 8859-9.
146 [2] Baltics. Now on 8859-10, except for Latvian.
147 [3] Also know as TIS 620.
148 [4] Nicknamed Latin0; the Euro sign as well as French and Finnish
149 letters that are missing from 8859-1 were added.
151 All cp* are also available as ibm-*, ms-*, and windows-* . See also
152 L<http://czyborra.com/charsets/codepages.html>.
154 Macintosh encodings don't seem to be registered in such entities as
155 IANA. "Canonical" names in Encode are based upon Apple's Tech Note
156 1150. See L<http://developer.apple.com/technotes/tn/tn1150.html>
159 =item KOI8 - De Facto Standard for the Cyrillic world
161 Though ISO-8859 does have ISO-8859-5, the KOI8 series is far more
162 popular in the Net. L<Encode> comes with the following KOI charsets.
163 For gory details, see L<http://czyborra.com/charsets/cyrillic.html>
165 ----------------------------------------------------------------
167 koi8-r cp878 [RFC1489]
169 ----------------------------------------------------------------
171 =item gsm0338 - Hentai Latin 1
173 GSM0338 is for GSM handsets. Though it shares alphanumerals with
174 ASCII, control character ranges and other parts are mapped very
175 differently, presumably to store Greek and Cyrillic alphabets.
176 This is also covered in Encode::Byte even though it is not an
177 "extended ASCII" encoding.
181 =head2 CJK: Chinese, Japanese, Korean (Multibyte)
183 Note that Vietnamese is listed above. Also read "Encoding vs Charset"
184 below. Also note that these are implemented in distinct modules by
185 countries, due the the size concerns (simplified Chinese is mapped
186 to 'CN', continental China, while traditional Chinese is mapped to
187 'TW', Taiwan). Please refer to their respective documentataion pages.
191 =item Encode::CN -- Continental China
193 Standard DOS/Win Macintosh Comment/Reference
194 ----------------------------------------------------------------
195 euc-cn [1] MacChineseSimp
197 gb12345-raw { GB12345 without CES }
198 gb2312-raw { GB2312 without CES }
201 ----------------------------------------------------------------
203 [1] GB2312 is aliased to this. See L<Microsoft-related naming mess>
204 [2] gbk is aliased to this. See L<Microsoft-related naming mess>
206 =item Encode::JP -- Japan
208 Standard DOS/Win Macintosh Comment/Reference
209 ----------------------------------------------------------------
211 shiftjis cp932 macJapanese
213 iso-2022-jp [RFC1468]
214 iso-2022-jp-1 [RFC2237]
215 jis0201-raw { JIS X 0201 (roman + halfwidth kana) without CES }
216 jis0208-raw { JIS X 0208 (Kanji + fullwidth kana) without CES }
217 jis0212-raw { JIS X 0212 (Extended Kanji) without CES }
218 ----------------------------------------------------------------
220 =item Encode::KR -- Korea
222 Standard DOS/Win Macintosh Comment/Reference
223 ----------------------------------------------------------------
224 euc-kr MacKorean [RFC1557]
226 iso-2022-kr [RFC1557]
227 johab [KS X 1001:1998, Annex 3]
228 ksc5601-raw { KSC5601 without CES }
229 ----------------------------------------------------------------
231 [1] ks_c_5601-1987, (x-)?windows-949, and uhc are aliased to this.
234 =item Encode::TW -- Taiwan
236 Standard DOS/Win Macintosh Comment/Reference
237 ----------------------------------------------------------------
238 big5-eten cp950 MacChineseTrad {big5 aliased to big5-eten}
240 ----------------------------------------------------------------
242 =item Encode::HanExtra -- More Chinese via CPAN
244 Due to size concerns, additional Chinese encodings below are
245 distributed separately on CPAN, under the name Encode::HanExtra.
247 Standard DOS/Win Macintosh Comment/Reference
248 ----------------------------------------------------------------
249 big5ext CMEX's Big5e Extension
250 big5plus CMEX's Big5+ Extension
251 cccii Chinese Character Code for Information Interchange
252 euc-tw EUC (Extended Unix Character)
253 gb18030 GBK with Traditional Characters
254 ----------------------------------------------------------------
256 =item Encode::JIS2K -- JIS X 0213 encodings via CPAN
258 Due to size concerns, additional Japanese encodings below are
259 distributed separately on CPAN, under the name Encode::JIS2K.
261 Standard DOS/Win Macintosh Comment/Reference
262 ----------------------------------------------------------------
268 ----------------------------------------------------------------
272 =head2 Miscellaneous encodings
278 See L<perlebcdic> for details.
280 ----------------------------------------------------------------
287 ----------------------------------------------------------------
289 =item Encode::Symbols
291 For symbols and dingbats.
293 ----------------------------------------------------------------
299 ----------------------------------------------------------------
301 =item Encode::MIME::Header
303 Strictly speaking, MIME header encoding documented in RFC 2047 is more
304 of encapsulation than encoding. But included anyway.
306 ----------------------------------------------------------------
307 MIME-Header [RFC2047]
310 ----------------------------------------------------------------
314 This one is not a name of encoding but a utility that lets you pick up
315 the most appropriate encoding for a data out of given I<suspects>. See
316 L<Encode::Guess> for details.
320 =head1 Unsupported encodings
322 The following encodings are not supported as yet; some because they
323 are rarely used, some because of technical difficulties. They may
324 be supported by external modules via CPAN in the future, however.
328 =item ISO-2022-JP-2 [RFC1554]
330 Not very popular yet. Needs Unicode Database or equivalent to
331 implement encode() (because it includes JIS X 0208/0212, KSC5601, and
332 GB2312 simultaneously, whose code points in Unicode overlap. So you
333 need to lookup the database to determine to what character set a given
334 Unicode character should belong).
336 =item ISO-2022-CN [RFC1922]
338 Not very popular. Needs CNS 11643-1 and -2 which are not available in
339 this module. CNS 11643 is supported (via euc-tw) in Encode::HanExtra.
340 Autrijus Tang may add support for this encoding in his module in future.
342 =item Various HP-UX encodings
344 The following are unsupported due to the lack of mapping data.
346 '8' - arabic8, greek8, hebrew8, kana8, thai8, and turkish8
347 '15' - japanese15, korean15, and roi15
349 =item Cyrillic encoding ISO-IR-111
351 Anton Tagunov doubts its usefulness.
353 =item ISO-8859-8-1 [Hebrew]
355 None of the Encode team knows Hebrew enough (ISO-8859-8, cp1255 and
356 MacHebrew are supported because and just because there were mappings
357 available at L<http://www.unicode.org/>). Contributions welcome.
359 =item ISIRI 3342, Iran System, ISIRI 2900 [Farsi]
363 =item Thai encoding TCVN
367 =item Vietnamese encodings VPS
369 Though Jungshik Shin has reported that Mozilla supports this encoding,
370 it was too late before 5.8.0 for us to add it. In the future, it
371 may be available via a separate module. See
372 L<http://lxr.mozilla.org/seamonkey/source/intl/uconv/ucvlatin/vps.uf>
374 L<http://lxr.mozilla.org/seamonkey/source/intl/uconv/ucvlatin/vps.ut>
375 if you are interested in helping us.
377 =item Various Mac encodings
379 The following are unsupported due to the lack of mapping data.
381 MacArmenian, MacBengali, MacBurmese, MacEthiopic
382 MacExtArabic, MacGeorgian, MacKannada, MacKhmer
383 MacLaotian, MacMalayalam, MacMongolian, MacOriya
384 MacSinhalese, MacTamil, MacTelugu, MacTibetan
387 The rest which are already available are based upon the vendor mappings
388 at L<http://www.unicode.org/Public/MAPPINGS/VENDORS/APPLE/> .
390 =item (Mac) Indic encodings
392 The maps for the following are available at L<http://www.unicode.org/>
393 but remain unsupport because those encodings need algorithmical
394 approach, currently unsupported by F<enc2xs>:
400 For details, please see C<Unicode mapping issues and notes:> at
401 L<http://www.unicode.org/Public/MAPPINGS/VENDORS/APPLE/DEVANAGA.TXT> .
403 I believe this issue is prevalent not only for Mac Indics but also in
404 other Indic encodings, but the above were the only Indic encodings
405 maps that I could find at L<http://www.unicode.org/> .
409 =head1 Encoding vs. Charset -- terminology
411 We are used to using the term (character) I<encoding> and I<character
412 set> interchangeably. But just as confusing the terms byte and
413 character is dangerous and the terms should be differentiated when
414 needed, we need to differentiate I<encoding> and I<character set>.
416 To understand that, here is a description of how we make computers
423 First we start with which characters to include. We call this
424 collection of characters I<character repertoire>.
428 Then we have to give each character a unique ID so your computer can
429 tell the difference between 'a' and 'A'. This itemized character
430 repertoire is now a I<character set>.
434 If your computer can grow the character set without further
435 processing, you can go ahead and use it. This is called a I<coded
436 character set> (CCS) or I<raw character encoding>. ASCII is used this
441 But in many cases, especially multi-byte CJK encodings, you have to
442 tweak a little more. Your network connection may not accept any data
443 with the Most Significant Bit set, and your computer may not be able to
444 tell if a given byte is a whole character or just half of it. So you
445 have to I<encode> the character set to use it.
447 A I<character encoding scheme> (CES) determines how to encode a given
448 character set, or a set of multiple character sets. 7bit ISO-2022 is
449 an example of a CES. You switch between character sets via I<escape
454 Technically, or mathematically, speaking, a character set encoded in
455 such a CES that maps character by character may form a CCS. EUC is such
456 an example. The CES of EUC is as follows:
466 Map such a character set that consists of 94 or 96 powered by N
467 members by adding 0x80 to each byte.
471 You can also use 0x8e and 0x8f to indicate that the following sequence of
472 characters belongs to yet another character set. To each following byte
473 is added the value 0x80.
477 By carefully looking at the encoded byte sequence, you can find that the
478 byte sequence conforms a unique number. In that sense, EUC is a CCS
479 generated by a CES above from up to four CCS (complicated?). UTF-8
480 falls into this category. See L<perlUnicode/"UTF-8"> to find out how
481 UTF-8 maps Unicode to a byte sequence.
483 You may also have found out by now why 7bit ISO-2022 cannot comprise
484 a CCS. If you look at a byte sequence \x21\x21, you can't tell if
485 it is two !'s or IDEOGRAPHIC SPACE. EUC maps the latter to \xA1\xA1
486 so you have no trouble differentiating between "!!". and S<" ">.
488 =head1 Encoding Classification (by Anton Tagunov and Dan Kogai)
490 This section tries to classify the supported encodings by their
491 applicability for information exchange over the Internet and to
492 choose the most suitable aliases to name them in the context of
499 To (en|de)code encodings marked by C<(**)>, you need
500 C<Encode::HanExtra>, available from CPAN.
506 US-ASCII UTF-8 ISO-8859-* KOI8-R
507 Shift_JIS EUC-JP ISO-2022-JP ISO-2022-JP-1
510 are registered with IANA as preferred MIME names and may
511 be used over the Internet.
513 C<Shift_JIS> has been officialized by JIS X 0208:1997.
514 L<Microsoft-related naming mess> gives details.
516 C<GB2312> is the IANA name for C<EUC-CN>.
517 See L<Microsoft-related naming mess> for details.
519 C<GB_2312-80> I<raw> encoding is available as C<gb2312-raw>
520 with Encode. See L<Encode::CN> for details.
525 have not been registered with IANA (as of March 2002) but
526 seem to be supported by major web browsers.
527 The IANA name for C<EUC-CN> is C<GB2312>.
532 See L<Microsoft-related naming mess> for details.
534 C<KS_C_5601-1987> I<raw> encoding is available as C<kcs5601-raw>
535 with Encode. See L<Encode::KR> for details.
537 UTF-16 UTF-16BE UTF-16LE
539 are IANA-registered C<charset>s. See [RFC 2781] for details.
540 Jungshik Shin reports that UTF-16 with a BOM is well accepted
541 by MS IE 5/6 and NS 4/6. Beware however that
547 C<UTF-16> support in any software you're going to be
548 using/interoperating with has probably been less tested
549 then C<UTF-8> support
553 C<UTF-8> coded data seamlessly passes traditional
554 command piping (C<cat>, C<more>, etc.) while C<UTF-16> coded
555 data is likely to cause confusion (with its zero bytes,
560 it is beyond the power of words to describe the way HTML browsers
561 encode non-C<ASCII> form data. To get a general impression, visit
562 L<http://ppewww.ph.gla.ac.uk/~flavell/charset/form-i18n.html>.
563 While encoding of form data has stabilized for C<UTF-8> encoded pages
564 (at least IE 5/6, NS 6, and Opera 6 behave consistently), be sure to
565 expect fun (and cross-browser discrepancies) with C<UTF-16> encoded
570 The rule of thumb is to use C<UTF-8> unless you know what
571 you're doing and unless you really benefit from using C<UTF-16>.
576 GB 18030 (**) (see links bellow)
579 are totally valid encodings but not registered at IANA.
580 The names under which they are listed here are probably the
581 most widely-known names for these encodings and are recommended
586 is a proprietary name.
588 =head2 Microsoft-related naming mess
590 Microsoft products misuse the following names:
596 Microsoft extension to C<EUC-KR>.
598 Proper names: C<CP949>, C<UHC>, C<x-windows-949> (as used by Mozilla).
600 See L<http://lists.w3.org/Archives/Public/ietf-charsets/2001AprJun/0033.html>
603 Encode aliases C<KS_C_5601-1987> to C<cp949> to reflect this common
604 misusage. I<Raw> C<KS_C_5601-1987> encoding is available as
607 See L<Encode::KR> for details.
611 Microsoft extension to C<EUC-CN>.
613 Proper names: C<CP936>, C<GBK>.
615 C<GB2312> has been registered in the C<EUC-CN> meaning at
616 IANA. This has partially repaired the situation: Microsoft's
617 C<GB2312> has become a superset of the official C<GB2312>.
619 Encode aliases C<GB2312> to C<euc-cn> in full agreement with
620 IANA registration. C<cp936> is supported separately.
621 I<Raw> C<GB_2312-80> encoding is available as C<gb2312-raw>.
623 See L<Encode::CN> for details.
627 Microsoft extension to C<Big5>.
629 Proper name: C<CP950>.
631 Encode separately supports C<Big5> and C<cp950>.
635 Microsoft's understanding of C<Shift_JIS>.
637 JIS has not endorsed the full Microsoft standard however.
638 The official C<Shift_JIS> includes only JIS X 0201 and JIS X 0208
639 character sets, while Microsoft has always used C<Shift_JIS>
640 to encode a wider character repertoire. See C<IANA> registration for
643 As a historical predecessor, Microsoft's variant
644 probably has more rights for the name, though it may be objected
645 that Microsoft shouldn't have used JIS as part of the name
648 Unambiguous name: C<CP932>. C<IANA> name (not used?): C<Windows-31J>.
650 Encode separately supports C<Shift_JIS> and C<cp932>.
658 =item character repertoire
660 A collection of unique characters. A I<character> set in the strictest
661 sense. At this stage, characters are not numbered.
663 =item coded character set (CCS)
665 A character set that is mapped in a way computers can use directly.
666 Many character encodings, including EUC, fall in this category.
668 =item character encoding scheme (CES)
670 An algorithm to map a character set to a byte sequence. You don't
671 have to be able to tell which character set a given byte sequence
672 belongs. 7-bit ISO-2022 is a CES but it cannot be a CCS. EUC is an
673 example of being both a CCS and CES.
675 =item charset (in MIME context)
677 has long been used in the meaning of C<encoding>, CES.
679 While the word combination C<character set> has lost this meaning
680 in MIME context since [RFC 2130], the C<charset> abbreviation has
681 retained it. This is how [RFC 2277] and [RFC 2278] bless C<charset>:
683 This document uses the term "charset" to mean a set of rules for
684 mapping from a sequence of octets to a sequence of characters, such
685 as the combination of a coded character set and a character encoding
686 scheme; this is also what is used as an identifier in MIME "charset="
687 parameters, and registered in the IANA charset registry ... (Note
688 that this is NOT a term used by other standards bodies, such as ISO).
693 Extended Unix Character. See ISO-2022.
697 A CES that was carefully designed to coexist with ASCII. There are a 7
698 bit version and an 8 bit version.
700 The 7 bit version switches character set via escape sequence so it
701 cannot form a CCS. Since this is more difficult to handle in programs
702 than the 8 bit version, the 7 bit version is not very popular except for
703 iso-2022-jp, the I<de facto> standard CES for e-mails.
705 The 8 bit version can form a CCS. EUC and ISO-8859 are two examples
706 thereof. Pre-5.6 perl could use them as string literals.
710 Short for I<Universal Character Set>. When you say just UCS, it means
715 ISO/IEC 10646 encoding form: Universal Character Set coded in two
720 A character set that aims to include all character repertoires of the
721 world. Many character sets in various national as well as industrial
722 standards have become, in a way, just subsets of Unicode.
726 Short for I<Unicode Transformation Format>. Determines how to map a
727 Unicode character into a byte sequence.
731 A UTF in 16-bit encoding. Can either be in big endian or little
732 endian. The big endian version is called UTF-16BE (equal to UCS-2 +
733 surrogate support) and the little endian version is called UTF-16LE.
741 L<Encode::CN>, L<Encode::JP>, L<Encode::KR>, L<Encode::TW>,
742 L<Encode::EBCDIC>, L<Encode::Symbol>
743 L<Encode::MIME::Header>, L<Encode::Guess>
751 European Computer Manufacturers Association
752 L<http://www.ecma.ch>
756 =item ECMA-035 (eq C<ISO-2022>)
758 L<http://www.ecma.ch/ecma1/STAND/ECMA-035.HTM>
760 The specification of ISO-2022 is available from the link above.
766 Internet Assigned Numbers Authority
767 L<http://www.iana.org/>
771 =item Assigned Charset Names by IANA
773 L<http://www.iana.org/assignments/character-sets>
775 Most of the C<canonical names> in Encode derive from this list
776 so you can directly apply the string you have extracted from MIME
777 header of mails and web pages.
783 International Organization for Standardization
784 L<http://www.iso.ch/>
788 Request For Comments -- need I say more?
789 L<http://www.rfc-editor.org/>, L<http://www.rfc.net/>,
790 L<http://www.faqs.org/rfcs/>
795 L<http://www.unicode.org/>
799 =item Unicode Glossary
801 L<http://www.unicode.org/glossary/>
803 The glossary of this document is based upon this site.
809 =head2 Other Notable Sites
815 L<http://czyborra.com/>
817 Contains a a lot of useful information, especially gory details of ISO
822 L<http://www.oreilly.com/people/authors/lunde/cjk_inf.html>
824 Somewhat obsolete (last update in 1996), but still useful. Also try
826 L<ftp://ftp.oreilly.com/pub/examples/nutshell/cjkv/pdf/GB18030_Summary.pdf>
828 You will find brief info on C<EUC-CN>, C<GBK> and mostly on C<GB 18030>.
830 =item Jungshik Shin's Hangul FAQ
832 L<http://jshin.net/faq>
834 And especially its subject 8.
836 L<http://jshin.net/faq/qa8.html>
838 A comprehensive overview of the Korean (C<KS *>) standards.
840 =item debian.org: "Introduction to i18n"
842 A brief description for most of the mentioned CJK encodings is
844 L<http://www.debian.org/doc/manuals/intro-i18n/ch-codes.en.html>
848 =head2 Offline sources
852 =item C<CJKV Information Processing> by Ken Lunde
854 CJKV Information Processing
855 1999 O'Reilly & Associates, ISBN : 1-56592-224-7
857 The modern successor of C<CJK.inf>.
859 Features a comprehensive coverage of CJKV character sets and
860 encodings along with many other issues faced by anyone trying
861 to better support CJKV languages/scripts in all the areas of
862 information processing.
864 To purchase this book, visit
865 L<http://www.oreilly.com/catalog/cjkvinfo/>
866 or your favourite bookstore.