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 iso-8859-1 latin1 [ISO]
66 ----------------------------------------------------------------
68 =head2 Encode::Unicode -- other Unicode encodings
70 Unicode coding schemes other than native utf8 are supported by
71 Encode::Unicode, which will be autoloaded on demand.
73 ----------------------------------------------------------------
74 UCS-2BE UCS-2, iso-10646-1 [IANA, UC]
82 ----------------------------------------------------------------
84 To find how (UCS-2|UTF-(16|32))(LE|BE)? differ from one another,
85 see L<Encode::Unicode>.
87 =head2 Encode::Byte -- Extended ASCII
89 Encode::Byte implements most single-byte encodings except for
90 Symbols and EBCDIC. The following encodings are based on single-byte
91 encodings implemented as extended ASCII. Most of them map
92 \x80-\xff (upper half) to non-ASCII characters.
96 =item ISO-8859 and corresponding vendor mappings
98 Since there are so many, they are presented in table format with
99 languages and corresponding encoding names by vendors. Note that
100 the table is sorted in order of ISO-8859 and the corresponding vendor
101 mappings are slightly different from that of ISO. See
102 L<http://czyborra.com/charsets/iso8859.html> for details.
104 Lang/Regions ISO/Other Std. DOS Windows Macintosh Others
105 ----------------------------------------------------------------
106 N. America (ASCII) cp437 AdobeStandardEncoding
108 W. Europe iso-8859-1 cp850 cp1252 MacRoman nextstep
110 cp860 (DOSPortuguese)
111 Cntrl. Europe iso-8859-2 cp852 cp1250 MacCentralEurRoman
115 Latin3 [1] iso-8859-3
116 Latin4 [2] iso-8859-4
117 Cyrillics iso-8859-5 cp855 cp1251 MacCyrillic
118 (See also next section) cp866 MacUkrainian
119 Arabic iso-8859-6 cp864 cp1256 MacArabic
121 Greek iso-8859-7 cp737 cp1253 MacGreek
123 Hebrew iso-8859-8 cp862 cp1255 MacHebrew
124 Turkish iso-8859-9 cp857 cp1254 MacTurkish
125 Nordics iso-8859-10 cp865
128 Thai iso-8859-11 [3] cp874 MacThai
129 (iso-8859-12 is nonexistent. Reserved for Indics?)
130 Baltics iso-8859-13 cp775 cp1257
132 Latin9 [4] iso-8859-15
134 Vietnamese viscii cp1258 MacVietnamese
135 ----------------------------------------------------------------
137 [1] Esperanto, Maltese, and Turkish. Turkish is now on 8859-9.
138 [2] Baltics. Now on 8859-10, except for Latvian.
139 [3] Also know as TIS 620.
140 [4] Nicknamed Latin0; the Euro sign as well as French and Finnish
141 letters that are missing from 8859-1 were added.
143 All cp* are also available as ibm-*, ms-*, and windows-* . See also
144 L<http://czyborra.com/charsets/codepages.html>.
146 Macintosh encodings don't seem to be registered in such entities as
147 IANA. "Canonical" names in Encode are based upon Apple's Tech Note
148 1150. See L<http://developer.apple.com/technotes/tn/tn1150.html>
151 =item KOI8 - De Facto Standard for the Cyrillic world
153 Though ISO-8859 does have ISO-8859-5, the KOI8 series is far more
154 popular in the Net. L<Encode> comes with the following KOI charsets.
155 For gory details, see L<http://czyborra.com/charsets/cyrillic.html>
157 ----------------------------------------------------------------
159 koi8-r cp878 [RFC1489]
161 ----------------------------------------------------------------
163 =item gsm0338 - Hentai Latin 1
165 GSM0338 is for GSM handsets. Though it shares alphanumerals with
166 ASCII, control character ranges and other parts are mapped very
167 differently, presumably to store Greek and Cyrillic alphabets.
168 This is also covered in Encode::Byte even though it is not an
169 "extended ASCII" encoding.
173 =head2 CJK: Chinese, Japanese, Korean (Multibyte)
175 Note that Vietnamese is listed above. Also read "Encoding vs Charset"
176 below. Also note that these are implemented in distinct modules by
177 countries, due the the size concerns (simplified Chinese is mapped
178 to 'CN', continental China, while traditional Chinese is mapped to
179 'TW', Taiwan). Please refer to their respective documentataion pages.
183 =item Encode::CN -- Continental China
185 Standard DOS/Win Macintosh Comment/Reference
186 ----------------------------------------------------------------
187 euc-cn [1] MacChineseSimp
189 gb12345-raw { GB12345 without CES }
190 gb2312-raw { GB2312 without CES }
193 ----------------------------------------------------------------
195 [1] GB2312 is aliased to this. See L<Microsoft-related naming mess>
196 [2] gbk is aliased to this. See L<Microsoft-related naming mess>
198 =item Encode::JP -- Japan
200 Standard DOS/Win Macintosh Comment/Reference
201 ----------------------------------------------------------------
203 shiftjis cp932 macJapanese
205 iso-2022-jp [RFC1468]
206 iso-2022-jp-1 [RFC2237]
207 jis0201-raw { JIS X 0201 (roman + halfwidth kana) without CES }
208 jis0208-raw { JIS X 0208 (Kanji + fullwidth kana) without CES }
209 jis0212-raw { JIS X 0212 (Extended Kanji) without CES }
210 ----------------------------------------------------------------
212 =item Encode::KR -- Korea
214 Standard DOS/Win Macintosh Comment/Reference
215 ----------------------------------------------------------------
216 euc-kr MacKorean [RFC1557]
218 iso-2022-kr [RFC1557]
219 johab [KS X 1001:1998, Annex 3]
220 ksc5601-raw { KSC5601 without CES }
221 ----------------------------------------------------------------
223 [1] ks_c_5601-1987, (x-)?windows-949, and uhc are aliased to this.
226 =item Encode::TW -- Taiwan
228 Standard DOS/Win Macintosh Comment/Reference
229 ----------------------------------------------------------------
230 big5-eten cp950 MacChineseTrad {big5 aliased to big5-eten}
232 ----------------------------------------------------------------
234 =item Encode::HanExtra -- More Chinese via CPAN
236 Due to size concerns, additional Chinese encodings below are
237 distributed separately on CPAN, under the name Encode::HanExtra.
239 Standard DOS/Win Macintosh Comment/Reference
240 ----------------------------------------------------------------
241 big5ext CMEX's Big5e Extension
242 big5plus CMEX's Big5+ Extension
243 cccii Chinese Character Code for Information Interchange
244 euc-tw EUC (Extended Unix Character)
245 gb18030 GBK with Traditional Characters
246 ----------------------------------------------------------------
248 =item Encode::JIS2K -- JIS X 0213 encodings via CPAN
250 Due to size concerns, additional Japanese encodings below are
251 distributed separately on CPAN, under the name Encode::JIS2K.
253 Standard DOS/Win Macintosh Comment/Reference
254 ----------------------------------------------------------------
260 ----------------------------------------------------------------
264 =head2 Miscellaneous encodings
270 See L<perlebcdic> for details.
272 ----------------------------------------------------------------
279 ----------------------------------------------------------------
281 =item Encode::Symbols
283 For symbols and dingbats.
285 ----------------------------------------------------------------
291 ----------------------------------------------------------------
293 =item Encode::MIME::Header
295 Strictly speaking, MIME header encoding documented in RFC 2047 is more
296 of encapsulation than encoding. But included anyway.
298 ----------------------------------------------------------------
299 MIME-Header [RFC2047]
302 ----------------------------------------------------------------
306 This one is not a name of encoding but a utility that lets you pick up
307 the most appropriate encoding for a data out of given I<suspects>. See
308 L<Encode::Guess> for details.
312 =head1 Unsupported encodings
314 The following encodings are not supported as yet; some because they
315 are rarely used, some because of technical difficulties. They may
316 be supported by external modules via CPAN in the future, however.
320 =item ISO-2022-JP-2 [RFC1554]
322 Not very popular yet. Needs Unicode Database or equivalent to
323 implement encode() (because it includes JIS X 0208/0212, KSC5601, and
324 GB2312 simultaneously, whose code points in Unicode overlap. So you
325 need to lookup the database to determine to what character set a given
326 Unicode character should belong).
328 =item ISO-2022-CN [RFC1922]
330 Not very popular. Needs CNS 11643-1 and -2 which are not available in
331 this module. CNS 11643 is supported (via euc-tw) in Encode::HanExtra.
332 Autrijus Tang may add support for this encoding in his module in future.
334 =item Various HP-UX encodings
336 The following are unsupported due to the lack of mapping data.
338 '8' - arabic8, greek8, hebrew8, kana8, thai8, and turkish8
339 '15' - japanese15, korean15, and roi15
341 =item Cyrillic encoding ISO-IR-111
343 Anton Tagunov doubts its usefulness.
345 =item ISO-8859-8-1 [Hebrew]
347 None of the Encode team knows Hebrew enough (ISO-8859-8, cp1255 and
348 MacHebrew are supported because and just because there were mappings
349 available at L<http://www.unicode.org/>). Contributions welcome.
351 =item ISIRI 3342, Iran System, ISIRI 2900 [Farsi]
355 =item Thai encoding TCVN
359 =item Vietnamese encodings VPS
361 Though Jungshik Shin has reported that Mozilla supports this encoding,
362 it was too late before 5.8.0 for us to add it. In the future, it
363 may be available via a separate module. See
364 L<http://lxr.mozilla.org/seamonkey/source/intl/uconv/ucvlatin/vps.uf>
366 L<http://lxr.mozilla.org/seamonkey/source/intl/uconv/ucvlatin/vps.ut>
367 if you are interested in helping us.
369 =item Various Mac encodings
371 The following are unsupported due to the lack of mapping data.
373 MacArmenian, MacBengali, MacBurmese, MacEthiopic
374 MacExtArabic, MacGeorgian, MacKannada, MacKhmer
375 MacLaotian, MacMalayalam, MacMongolian, MacOriya
376 MacSinhalese, MacTamil, MacTelugu, MacTibetan
379 The rest which are already available are based upon the vendor mappings
380 at L<http://www.unicode.org/Public/MAPPINGS/VENDORS/APPLE/> .
382 =item (Mac) Indic encodings
384 The maps for the following are available at L<http://www.unicode.org/>
385 but remain unsupport because those encodings need algorithmical
386 approach, currently unsupported by F<enc2xs>:
392 For details, please see C<Unicode mapping issues and notes:> at
393 L<http://www.unicode.org/Public/MAPPINGS/VENDORS/APPLE/DEVANAGA.TXT> .
395 I believe this issue is prevalent not only for Mac Indics but also in
396 other Indic encodings, but the above were the only Indic encodings
397 maps that I could find at L<http://www.unicode.org/> .
401 =head1 Encoding vs. Charset -- terminology
403 We are used to using the term (character) I<encoding> and I<character
404 set> interchangeably. But just as confusing the terms byte and
405 character is dangerous and the terms should be differentiated when
406 needed, we need to differentiate I<encoding> and I<character set>.
408 To understand that, here is a description of how we make computers
415 First we start with which characters to include. We call this
416 collection of characters I<character repertoire>.
420 Then we have to give each character a unique ID so your computer can
421 tell the difference between 'a' and 'A'. This itemized character
422 repertoire is now a I<character set>.
426 If your computer can grow the character set without further
427 processing, you can go ahead and use it. This is called a I<coded
428 character set> (CCS) or I<raw character encoding>. ASCII is used this
433 But in many cases, especially multi-byte CJK encodings, you have to
434 tweak a little more. Your network connection may not accept any data
435 with the Most Significant Bit set, and your computer may not be able to
436 tell if a given byte is a whole character or just half of it. So you
437 have to I<encode> the character set to use it.
439 A I<character encoding scheme> (CES) determines how to encode a given
440 character set, or a set of multiple character sets. 7bit ISO-2022 is
441 an example of a CES. You switch between character sets via I<escape
446 Technically, or mathematically, speaking, a character set encoded in
447 such a CES that maps character by character may form a CCS. EUC is such
448 an example. The CES of EUC is as follows:
458 Map such a character set that consists of 94 or 96 powered by N
459 members by adding 0x80 to each byte.
463 You can also use 0x8e and 0x8f to indicate that the following sequence of
464 characters belongs to yet another character set. To each following byte
465 is added the value 0x80.
469 By carefully looking at the encoded byte sequence, you can find that the
470 byte sequence conforms a unique number. In that sense, EUC is a CCS
471 generated by a CES above from up to four CCS (complicated?). UTF-8
472 falls into this category. See L<perlUnicode/"UTF-8"> to find out how
473 UTF-8 maps Unicode to a byte sequence.
475 You may also have found out by now why 7bit ISO-2022 cannot comprise
476 a CCS. If you look at a byte sequence \x21\x21, you can't tell if
477 it is two !'s or IDEOGRAPHIC SPACE. EUC maps the latter to \xA1\xA1
478 so you have no trouble differentiating between "!!". and S<" ">.
480 =head1 Encoding Classification (by Anton Tagunov and Dan Kogai)
482 This section tries to classify the supported encodings by their
483 applicability for information exchange over the Internet and to
484 choose the most suitable aliases to name them in the context of
491 To (en|de)code encodings marked by C<(**)>, you need
492 C<Encode::HanExtra>, available from CPAN.
498 US-ASCII UTF-8 ISO-8859-* KOI8-R
499 Shift_JIS EUC-JP ISO-2022-JP ISO-2022-JP-1
502 are registered with IANA as preferred MIME names and may
503 be used over the Internet.
505 C<Shift_JIS> has been officialized by JIS X 0208:1997.
506 L<Microsoft-related naming mess> gives details.
508 C<GB2312> is the IANA name for C<EUC-CN>.
509 See L<Microsoft-related naming mess> for details.
511 C<GB_2312-80> I<raw> encoding is available as C<gb2312-raw>
512 with Encode. See L<Encode::CN> for details.
517 have not been registered with IANA (as of March 2002) but
518 seem to be supported by major web browsers.
519 The IANA name for C<EUC-CN> is C<GB2312>.
524 See L<Microsoft-related naming mess> for details.
526 C<KS_C_5601-1987> I<raw> encoding is available as C<kcs5601-raw>
527 with Encode. See L<Encode::KR> for details.
529 UTF-16 UTF-16BE UTF-16LE
531 are IANA-registered C<charset>s. See [RFC 2781] for details.
532 Jungshik Shin reports that UTF-16 with a BOM is well accepted
533 by MS IE 5/6 and NS 4/6. Beware however that
539 C<UTF-16> support in any software you're going to be
540 using/interoperating with has probably been less tested
541 then C<UTF-8> support
545 C<UTF-8> coded data seamlessly passes traditional
546 command piping (C<cat>, C<more>, etc.) while C<UTF-16> coded
547 data is likely to cause confusion (with its zero bytes,
552 it is beyond the power of words to describe the way HTML browsers
553 encode non-C<ASCII> form data. To get a general impression, visit
554 L<http://ppewww.ph.gla.ac.uk/~flavell/charset/form-i18n.html>.
555 While encoding of form data has stabilized for C<UTF-8> encoded pages
556 (at least IE 5/6, NS 6, and Opera 6 behave consistently), be sure to
557 expect fun (and cross-browser discrepancies) with C<UTF-16> encoded
562 The rule of thumb is to use C<UTF-8> unless you know what
563 you're doing and unless you really benefit from using C<UTF-16>.
568 GB 18030 (**) (see links bellow)
571 are totally valid encodings but not registered at IANA.
572 The names under which they are listed here are probably the
573 most widely-known names for these encodings and are recommended
578 is a proprietary name.
580 =head2 Microsoft-related naming mess
582 Microsoft products misuse the following names:
588 Microsoft extension to C<EUC-KR>.
590 Proper names: C<CP949>, C<UHC>, C<x-windows-949> (as used by Mozilla).
592 See L<http://lists.w3.org/Archives/Public/ietf-charsets/2001AprJun/0033.html>
595 Encode aliases C<KS_C_5601-1987> to C<cp949> to reflect this common
596 misusage. I<Raw> C<KS_C_5601-1987> encoding is available as
599 See L<Encode::KR> for details.
603 Microsoft extension to C<EUC-CN>.
605 Proper names: C<CP936>, C<GBK>.
607 C<GB2312> has been registered in the C<EUC-CN> meaning at
608 IANA. This has partially repaired the situation: Microsoft's
609 C<GB2312> has become a superset of the official C<GB2312>.
611 Encode aliases C<GB2312> to C<euc-cn> in full agreement with
612 IANA registration. C<cp936> is supported separately.
613 I<Raw> C<GB_2312-80> encoding is available as C<gb2312-raw>.
615 See L<Encode::CN> for details.
619 Microsoft extension to C<Big5>.
621 Proper name: C<CP950>.
623 Encode separately supports C<Big5> and C<cp950>.
627 Microsoft's understanding of C<Shift_JIS>.
629 JIS has not endorsed the full Microsoft standard however.
630 The official C<Shift_JIS> includes only JIS X 0201 and JIS X 0208
631 character sets, while Microsoft has always used C<Shift_JIS>
632 to encode a wider character repertoire. See C<IANA> registration for
635 As a historical predecessor, Microsoft's variant
636 probably has more rights for the name, though it may be objected
637 that Microsoft shouldn't have used JIS as part of the name
640 Unambiguous name: C<CP932>. C<IANA> name (not used?): C<Windows-31J>.
642 Encode separately supports C<Shift_JIS> and C<cp932>.
650 =item character repertoire
652 A collection of unique characters. A I<character> set in the strictest
653 sense. At this stage, characters are not numbered.
655 =item coded character set (CCS)
657 A character set that is mapped in a way computers can use directly.
658 Many character encodings, including EUC, fall in this category.
660 =item character encoding scheme (CES)
662 An algorithm to map a character set to a byte sequence. You don't
663 have to be able to tell which character set a given byte sequence
664 belongs. 7-bit ISO-2022 is a CES but it cannot be a CCS. EUC is an
665 example of being both a CCS and CES.
667 =item charset (in MIME context)
669 has long been used in the meaning of C<encoding>, CES.
671 While the word combination C<character set> has lost this meaning
672 in MIME context since [RFC 2130], the C<charset> abbreviation has
673 retained it. This is how [RFC 2277] and [RFC 2278] bless C<charset>:
675 This document uses the term "charset" to mean a set of rules for
676 mapping from a sequence of octets to a sequence of characters, such
677 as the combination of a coded character set and a character encoding
678 scheme; this is also what is used as an identifier in MIME "charset="
679 parameters, and registered in the IANA charset registry ... (Note
680 that this is NOT a term used by other standards bodies, such as ISO).
685 Extended Unix Character. See ISO-2022.
689 A CES that was carefully designed to coexist with ASCII. There are a 7
690 bit version and an 8 bit version.
692 The 7 bit version switches character set via escape sequence so it
693 cannot form a CCS. Since this is more difficult to handle in programs
694 than the 8 bit version, the 7 bit version is not very popular except for
695 iso-2022-jp, the I<de facto> standard CES for e-mails.
697 The 8 bit version can form a CCS. EUC and ISO-8859 are two examples
698 thereof. Pre-5.6 perl could use them as string literals.
702 Short for I<Universal Character Set>. When you say just UCS, it means
707 ISO/IEC 10646 encoding form: Universal Character Set coded in two
712 A character set that aims to include all character repertoires of the
713 world. Many character sets in various national as well as industrial
714 standards have become, in a way, just subsets of Unicode.
718 Short for I<Unicode Transformation Format>. Determines how to map a
719 Unicode character into a byte sequence.
723 A UTF in 16-bit encoding. Can either be in big endian or little
724 endian. The big endian version is called UTF-16BE (equal to UCS-2 +
725 surrogate support) and the little endian version is called UTF-16LE.
733 L<Encode::CN>, L<Encode::JP>, L<Encode::KR>, L<Encode::TW>,
734 L<Encode::EBCDIC>, L<Encode::Symbol>
735 L<Encode::MIME::Header>, L<Encode::Guess>
743 European Computer Manufacturers Association
744 L<http://www.ecma.ch>
748 =item ECMA-035 (eq C<ISO-2022>)
750 L<http://www.ecma.ch/ecma1/STAND/ECMA-035.HTM>
752 The specification of ISO-2022 is available from the link above.
758 Internet Assigned Numbers Authority
759 L<http://www.iana.org/>
763 =item Assigned Charset Names by IANA
765 L<http://www.iana.org/assignments/character-sets>
767 Most of the C<canonical names> in Encode derive from this list
768 so you can directly apply the string you have extracted from MIME
769 header of mails and web pages.
775 International Organization for Standardization
776 L<http://www.iso.ch/>
780 Request For Comments -- need I say more?
781 L<http://www.rfc-editor.org/>, L<http://www.rfc.net/>,
782 L<http://www.faqs.org/rfcs/>
787 L<http://www.unicode.org/>
791 =item Unicode Glossary
793 L<http://www.unicode.org/glossary/>
795 The glossary of this document is based upon this site.
801 =head2 Other Notable Sites
807 L<http://czyborra.com/>
809 Contains a a lot of useful information, especially gory details of ISO
814 L<http://www.oreilly.com/people/authors/lunde/cjk_inf.html>
816 Somewhat obsolete (last update in 1996), but still useful. Also try
818 L<ftp://ftp.oreilly.com/pub/examples/nutshell/cjkv/pdf/GB18030_Summary.pdf>
820 You will find brief info on C<EUC-CN>, C<GBK> and mostly on C<GB 18030>.
822 =item Jungshik Shin's Hangul FAQ
824 L<http://jshin.net/faq>
826 And especially its subject 8.
828 L<http://jshin.net/faq/qa8.html>
830 A comprehensive overview of the Korean (C<KS *>) standards.
832 =item debian.org: "Introduction to i18n"
834 A brief description for most of the mentioned CJK encodings is
836 L<http://www.debian.org/doc/manuals/intro-i18n/ch-codes.en.html>
840 =head2 Offline sources
844 =item C<CJKV Information Processing> by Ken Lunde
846 CJKV Information Processing
847 1999 O'Reilly & Associates, ISBN : 1-56592-224-7
849 The modern successor of C<CJK.inf>.
851 Features a comprehensive coverage of CJKV character sets and
852 encodings along with many other issues faced by anyone trying
853 to better support CJKV languages/scripts in all the areas of
854 information processing.
856 To purchase this book, visit
857 L<http://www.oreilly.com/catalog/cjkvinfo/>
858 or your favourite bookstore.