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 ----------------------------------------------------------------
63 ascii US-ascii ISO-646-US [ECMA]
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
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] TIS 620 + Non-Breaking Space (0xA0 / U+00A0)
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 to 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 documentation 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 the 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. However, their support in modern
305 world is imperative so they are supported.
307 ----------------------------------------------------------------
308 MIME-Header [RFC2047]
311 ----------------------------------------------------------------
315 This one is not a name of encoding but a utility that lets you pick up
316 the most appropriate encoding for a data out of given I<suspects>. See
317 L<Encode::Guess> for details.
321 =head1 Unsupported encodings
323 The following encodings are not supported as yet; some because they
324 are rarely used, some because of technical difficulties. They may
325 be supported by external modules via CPAN in the future, however.
329 =item ISO-2022-JP-2 [RFC1554]
331 Not very popular yet. Needs Unicode Database or equivalent to
332 implement encode() (because it includes JIS X 0208/0212, KSC5601, and
333 GB2312 simultaneously, whose code points in Unicode overlap. So you
334 need to lookup the database to determine to what character set a given
335 Unicode character should belong).
337 =item ISO-2022-CN [RFC1922]
339 Not very popular. Needs CNS 11643-1 and -2 which are not available in
340 this module. CNS 11643 is supported (via euc-tw) in Encode::HanExtra.
341 Autrijus Tang may add support for this encoding in his module in future.
343 =item Various HP-UX encodings
345 The following are unsupported due to the lack of mapping data.
347 '8' - arabic8, greek8, hebrew8, kana8, thai8, and turkish8
348 '15' - japanese15, korean15, and roi15
350 =item Cyrillic encoding ISO-IR-111
352 Anton Tagunov doubts its usefulness.
354 =item ISO-8859-8-1 [Hebrew]
356 None of the Encode team knows Hebrew enough (ISO-8859-8, cp1255 and
357 MacHebrew are supported because and just because there were mappings
358 available at L<http://www.unicode.org/>). Contributions welcome.
360 =item ISIRI 3342, Iran System, ISIRI 2900 [Farsi]
364 =item Thai encoding TCVN
368 =item Vietnamese encodings VPS
370 Though Jungshik Shin has reported that Mozilla supports this encoding,
371 it was too late before 5.8.0 for us to add it. In the future, it
372 may be available via a separate module. See
373 L<http://lxr.mozilla.org/seamonkey/source/intl/uconv/ucvlatin/vps.uf>
375 L<http://lxr.mozilla.org/seamonkey/source/intl/uconv/ucvlatin/vps.ut>
376 if you are interested in helping us.
378 =item Various Mac encodings
380 The following are unsupported due to the lack of mapping data.
382 MacArmenian, MacBengali, MacBurmese, MacEthiopic
383 MacExtArabic, MacGeorgian, MacKannada, MacKhmer
384 MacLaotian, MacMalayalam, MacMongolian, MacOriya
385 MacSinhalese, MacTamil, MacTelugu, MacTibetan
388 The rest which are already available are based upon the vendor mappings
389 at L<http://www.unicode.org/Public/MAPPINGS/VENDORS/APPLE/> .
391 =item (Mac) Indic encodings
393 The maps for the following are available at L<http://www.unicode.org/>
394 but remain unsupport because those encodings need algorithmical
395 approach, currently unsupported by F<enc2xs>:
401 For details, please see C<Unicode mapping issues and notes:> at
402 L<http://www.unicode.org/Public/MAPPINGS/VENDORS/APPLE/DEVANAGA.TXT> .
404 I believe this issue is prevalent not only for Mac Indics but also in
405 other Indic encodings, but the above were the only Indic encodings
406 maps that I could find at L<http://www.unicode.org/> .
410 =head1 Encoding vs. Charset -- terminology
412 We are used to using the term (character) I<encoding> and I<character
413 set> interchangeably. But just as confusing the terms byte and
414 character is dangerous and the terms should be differentiated when
415 needed, we need to differentiate I<encoding> and I<character set>.
417 To understand that, here is a description of how we make computers
424 First we start with which characters to include. We call this
425 collection of characters I<character repertoire>.
429 Then we have to give each character a unique ID so your computer can
430 tell the difference between 'a' and 'A'. This itemized character
431 repertoire is now a I<character set>.
435 If your computer can grow the character set without further
436 processing, you can go ahead and use it. This is called a I<coded
437 character set> (CCS) or I<raw character encoding>. ASCII is used this
442 But in many cases, especially multi-byte CJK encodings, you have to
443 tweak a little more. Your network connection may not accept any data
444 with the Most Significant Bit set, and your computer may not be able to
445 tell if a given byte is a whole character or just half of it. So you
446 have to I<encode> the character set to use it.
448 A I<character encoding scheme> (CES) determines how to encode a given
449 character set, or a set of multiple character sets. 7bit ISO-2022 is
450 an example of a CES. You switch between character sets via I<escape
455 Technically, or mathematically, speaking, a character set encoded in
456 such a CES that maps character by character may form a CCS. EUC is such
457 an example. The CES of EUC is as follows:
467 Map such a character set that consists of 94 or 96 powered by N
468 members by adding 0x80 to each byte.
472 You can also use 0x8e and 0x8f to indicate that the following sequence of
473 characters belongs to yet another character set. To each following byte
474 is added the value 0x80.
478 By carefully looking at the encoded byte sequence, you can find that the
479 byte sequence conforms a unique number. In that sense, EUC is a CCS
480 generated by a CES above from up to four CCS (complicated?). UTF-8
481 falls into this category. See L<perlUnicode/"UTF-8"> to find out how
482 UTF-8 maps Unicode to a byte sequence.
484 You may also have found out by now why 7bit ISO-2022 cannot comprise
485 a CCS. If you look at a byte sequence \x21\x21, you can't tell if
486 it is two !'s or IDEOGRAPHIC SPACE. EUC maps the latter to \xA1\xA1
487 so you have no trouble differentiating between "!!". and S<" ">.
489 =head1 Encoding Classification (by Anton Tagunov and Dan Kogai)
491 This section tries to classify the supported encodings by their
492 applicability for information exchange over the Internet and to
493 choose the most suitable aliases to name them in the context of
500 To (en|de)code encodings marked by C<(**)>, you need
501 C<Encode::HanExtra>, available from CPAN.
507 US-ASCII UTF-8 ISO-8859-* KOI8-R
508 Shift_JIS EUC-JP ISO-2022-JP ISO-2022-JP-1
511 are registered with IANA as preferred MIME names and may
512 be used over the Internet.
514 C<Shift_JIS> has been officialized by JIS X 0208:1997.
515 L<Microsoft-related naming mess> gives details.
517 C<GB2312> is the IANA name for C<EUC-CN>.
518 See L<Microsoft-related naming mess> for details.
520 C<GB_2312-80> I<raw> encoding is available as C<gb2312-raw>
521 with Encode. See L<Encode::CN> for details.
526 have not been registered with IANA (as of March 2002) but
527 seem to be supported by major web browsers.
528 The IANA name for C<EUC-CN> is C<GB2312>.
533 See L<Microsoft-related naming mess> for details.
535 C<KS_C_5601-1987> I<raw> encoding is available as C<kcs5601-raw>
536 with Encode. See L<Encode::KR> for details.
538 UTF-16 UTF-16BE UTF-16LE
540 are IANA-registered C<charset>s. See [RFC 2781] for details.
541 Jungshik Shin reports that UTF-16 with a BOM is well accepted
542 by MS IE 5/6 and NS 4/6. Beware however that
548 C<UTF-16> support in any software you're going to be
549 using/interoperating with has probably been less tested
550 then C<UTF-8> support
554 C<UTF-8> coded data seamlessly passes traditional
555 command piping (C<cat>, C<more>, etc.) while C<UTF-16> coded
556 data is likely to cause confusion (with its zero bytes,
561 it is beyond the power of words to describe the way HTML browsers
562 encode non-C<ASCII> form data. To get a general impression, visit
563 L<http://ppewww.ph.gla.ac.uk/~flavell/charset/form-i18n.html>.
564 While encoding of form data has stabilized for C<UTF-8> encoded pages
565 (at least IE 5/6, NS 6, and Opera 6 behave consistently), be sure to
566 expect fun (and cross-browser discrepancies) with C<UTF-16> encoded
571 The rule of thumb is to use C<UTF-8> unless you know what
572 you're doing and unless you really benefit from using C<UTF-16>.
577 GB 18030 (**) (see links bellow)
580 are totally valid encodings but not registered at IANA.
581 The names under which they are listed here are probably the
582 most widely-known names for these encodings and are recommended
587 is a proprietary name.
589 =head2 Microsoft-related naming mess
591 Microsoft products misuse the following names:
597 Microsoft extension to C<EUC-KR>.
599 Proper names: C<CP949>, C<UHC>, C<x-windows-949> (as used by Mozilla).
601 See L<http://lists.w3.org/Archives/Public/ietf-charsets/2001AprJun/0033.html>
604 Encode aliases C<KS_C_5601-1987> to C<cp949> to reflect this common
605 misusage. I<Raw> C<KS_C_5601-1987> encoding is available as
608 See L<Encode::KR> for details.
612 Microsoft extension to C<EUC-CN>.
614 Proper names: C<CP936>, C<GBK>.
616 C<GB2312> has been registered in the C<EUC-CN> meaning at
617 IANA. This has partially repaired the situation: Microsoft's
618 C<GB2312> has become a superset of the official C<GB2312>.
620 Encode aliases C<GB2312> to C<euc-cn> in full agreement with
621 IANA registration. C<cp936> is supported separately.
622 I<Raw> C<GB_2312-80> encoding is available as C<gb2312-raw>.
624 See L<Encode::CN> for details.
628 Microsoft extension to C<Big5>.
630 Proper name: C<CP950>.
632 Encode separately supports C<Big5> and C<cp950>.
636 Microsoft's understanding of C<Shift_JIS>.
638 JIS has not endorsed the full Microsoft standard however.
639 The official C<Shift_JIS> includes only JIS X 0201 and JIS X 0208
640 character sets, while Microsoft has always used C<Shift_JIS>
641 to encode a wider character repertoire. See C<IANA> registration for
644 As a historical predecessor, Microsoft's variant
645 probably has more rights for the name, though it may be objected
646 that Microsoft shouldn't have used JIS as part of the name
649 Unambiguous name: C<CP932>. C<IANA> name (not used?): C<Windows-31J>.
651 Encode separately supports C<Shift_JIS> and C<cp932>.
659 =item character repertoire
661 A collection of unique characters. A I<character> set in the strictest
662 sense. At this stage, characters are not numbered.
664 =item coded character set (CCS)
666 A character set that is mapped in a way computers can use directly.
667 Many character encodings, including EUC, fall in this category.
669 =item character encoding scheme (CES)
671 An algorithm to map a character set to a byte sequence. You don't
672 have to be able to tell which character set a given byte sequence
673 belongs. 7-bit ISO-2022 is a CES but it cannot be a CCS. EUC is an
674 example of being both a CCS and CES.
676 =item charset (in MIME context)
678 has long been used in the meaning of C<encoding>, CES.
680 While the word combination C<character set> has lost this meaning
681 in MIME context since [RFC 2130], the C<charset> abbreviation has
682 retained it. This is how [RFC 2277] and [RFC 2278] bless C<charset>:
684 This document uses the term "charset" to mean a set of rules for
685 mapping from a sequence of octets to a sequence of characters, such
686 as the combination of a coded character set and a character encoding
687 scheme; this is also what is used as an identifier in MIME "charset="
688 parameters, and registered in the IANA charset registry ... (Note
689 that this is NOT a term used by other standards bodies, such as ISO).
694 Extended Unix Character. See ISO-2022.
698 A CES that was carefully designed to coexist with ASCII. There are a 7
699 bit version and an 8 bit version.
701 The 7 bit version switches character set via escape sequence so it
702 cannot form a CCS. Since this is more difficult to handle in programs
703 than the 8 bit version, the 7 bit version is not very popular except for
704 iso-2022-jp, the I<de facto> standard CES for e-mails.
706 The 8 bit version can form a CCS. EUC and ISO-8859 are two examples
707 thereof. Pre-5.6 perl could use them as string literals.
711 Short for I<Universal Character Set>. When you say just UCS, it means
716 ISO/IEC 10646 encoding form: Universal Character Set coded in two
721 A character set that aims to include all character repertoires of the
722 world. Many character sets in various national as well as industrial
723 standards have become, in a way, just subsets of Unicode.
727 Short for I<Unicode Transformation Format>. Determines how to map a
728 Unicode character into a byte sequence.
732 A UTF in 16-bit encoding. Can either be in big endian or little
733 endian. The big endian version is called UTF-16BE (equal to UCS-2 +
734 surrogate support) and the little endian version is called UTF-16LE.
742 L<Encode::CN>, L<Encode::JP>, L<Encode::KR>, L<Encode::TW>,
743 L<Encode::EBCDIC>, L<Encode::Symbol>
744 L<Encode::MIME::Header>, L<Encode::Guess>
752 European Computer Manufacturers Association
753 L<http://www.ecma.ch>
757 =item ECMA-035 (eq C<ISO-2022>)
759 L<http://www.ecma.ch/ecma1/STAND/ECMA-035.HTM>
761 The specification of ISO-2022 is available from the link above.
767 Internet Assigned Numbers Authority
768 L<http://www.iana.org/>
772 =item Assigned Charset Names by IANA
774 L<http://www.iana.org/assignments/character-sets>
776 Most of the C<canonical names> in Encode derive from this list
777 so you can directly apply the string you have extracted from MIME
778 header of mails and web pages.
784 International Organization for Standardization
785 L<http://www.iso.ch/>
789 Request For Comments -- need I say more?
790 L<http://www.rfc-editor.org/>, L<http://www.rfc.net/>,
791 L<http://www.faqs.org/rfcs/>
796 L<http://www.unicode.org/>
800 =item Unicode Glossary
802 L<http://www.unicode.org/glossary/>
804 The glossary of this document is based upon this site.
810 =head2 Other Notable Sites
816 L<http://czyborra.com/>
818 Contains a a lot of useful information, especially gory details of ISO
823 L<http://www.oreilly.com/people/authors/lunde/cjk_inf.html>
825 Somewhat obsolete (last update in 1996), but still useful. Also try
827 L<ftp://ftp.oreilly.com/pub/examples/nutshell/cjkv/pdf/GB18030_Summary.pdf>
829 You will find brief info on C<EUC-CN>, C<GBK> and mostly on C<GB 18030>.
831 =item Jungshik Shin's Hangul FAQ
833 L<http://jshin.net/faq>
835 And especially its subject 8.
837 L<http://jshin.net/faq/qa8.html>
839 A comprehensive overview of the Korean (C<KS *>) standards.
841 =item debian.org: "Introduction to i18n"
843 A brief description for most of the mentioned CJK encodings is
845 L<http://www.debian.org/doc/manuals/intro-i18n/ch-codes.en.html>
849 =head2 Offline sources
853 =item C<CJKV Information Processing> by Ken Lunde
855 CJKV Information Processing
856 1999 O'Reilly & Associates, ISBN : 1-56592-224-7
858 The modern successor of C<CJK.inf>.
860 Features a comprehensive coverage of CJKV character sets and
861 encodings along with many other issues faced by anyone trying
862 to better support CJKV languages/scripts in all the areas of
863 information processing.
865 To purchase this book, visit
866 L<http://www.oreilly.com/catalog/cjkvinfo/>
867 or your favourite bookstore.