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
206 iso-2022-jp [RFC1468]
207 iso-2022-jp-1 [RFC2237]
208 jis0201-raw { JIS X 0201 (roman + halfwidth kana) without CES }
209 jis0208-raw { JIS X 0208 (Kanji + fullwidth kana) without CES }
210 jis0212-raw { JIS X 0212 (Extended Kanji) without CES }
211 ----------------------------------------------------------------
213 =item Encode::KR -- Korea
215 Standard DOS/Win Macintosh Comment/Reference
216 ----------------------------------------------------------------
217 euc-kr MacKorean [RFC1557]
219 iso-2022-kr [RFC1557]
220 johab [KS X 1001:1998, Annex 3]
221 ksc5601-raw { KSC5601 without CES }
222 ----------------------------------------------------------------
224 [1] ks_c_5601-1987, (x-)?windows-949, and uhc are aliased to this.
227 =item Encode::TW -- Taiwan
229 Standard DOS/Win Macintosh Comment/Reference
230 ----------------------------------------------------------------
231 big5-eten cp950 MacChineseTrad {big5 aliased to big5-eten}
233 ----------------------------------------------------------------
235 =item Encode::HanExtra -- More Chinese via CPAN
237 Due to size concerns, additional Chinese encodings below are
238 distributed separately on CPAN, under the name Encode::HanExtra.
240 Standard DOS/Win Macintosh Comment/Reference
241 ----------------------------------------------------------------
245 ----------------------------------------------------------------
249 =head2 Miscellaneous encodings
255 See L<perlebcdic> for details.
257 ----------------------------------------------------------------
264 ----------------------------------------------------------------
266 =item Encode::Symbols
268 For symbols and dingbats.
270 ----------------------------------------------------------------
276 ----------------------------------------------------------------
280 =head1 Unsupported encodings
282 The following encodings are not supported as yet; some because they
283 are rarely used, some because of technical difficulties. They may
284 be supported by external modules via CPAN in the future, however.
288 =item ISO-2022-JP-2 [RFC1554]
290 Not very popular yet. Needs Unicode Database or equivalent to
291 implement encode() (because it includes JIS X 0208/0212, KSC5601, and
292 GB2312 simultaneously, whose code points in Unicode overlap. So you
293 need to lookup the database to determine to what character set a given
294 Unicode character should belong).
296 =item ISO-2022-CN [RFC1922]
298 Not very popular. Needs CNS 11643-1 and -2 which are not available in
299 this module. CNS 11643 is supported (via euc-tw) in Encode::HanExtra.
300 Autrijus Tang may add support for this encoding in his module in future.
302 =item Various HP-UX encodings
304 The following are unsupported due to the lack of mapping data.
306 '8' - arabic8, greek8, hebrew8, kana8, thai8, and turkish8
307 '15' - japanese15, korean15, and roi15
309 =item Cyrillic encoding ISO-IR-111
311 Anton Tagunov doubts its usefulness.
313 =item ISO-8859-8-1 [Hebrew]
315 None of the Encode team knows Hebrew enough (ISO-8859-8, cp1255 and
316 MacHebrew are supported because and just because there were mappings
317 available at L<http://www.unicode.org/>). Contributions welcome.
319 =item ISIRI 3342, Iran System, ISIRI 2900 [Farsi]
323 =item Thai encoding TCVN
327 =item Vietnamese encodings VPS
329 Though Jungshik Shin has reported that Mozilla supports this encoding,
330 it was too late before 5.8.0 for us to add it. In the future, it
331 may be available via a separate module. See
332 L<http://lxr.mozilla.org/seamonkey/source/intl/uconv/ucvlatin/vps.uf>
334 L<http://lxr.mozilla.org/seamonkey/source/intl/uconv/ucvlatin/vps.ut>
335 if you are interested in helping us.
337 =item Various Mac encodings
339 The following are unsupported due to the lack of mapping data.
341 MacArmenian, MacBengali, MacBurmese, MacEthiopic
342 MacExtArabic, MacGeorgian, MacKannada, MacKhmer
343 MacLaotian, MacMalayalam, MacMongolian, MacOriya
344 MacSinhalese, MacTamil, MacTelugu, MacTibetan
347 The rest which are already available are based upon the vendor mappings
348 at L<http://www.unicode.org/Public/MAPPINGS/VENDORS/APPLE/> .
350 =item (Mac) Indic encodings
352 The maps for the following are available at L<http://www.unicode.org/>
353 but remain unsupport because those encodings need algorithmical
354 approach, currently unsupported by F<enc2xs>:
360 For details, please see C<Unicode mapping issues and notes:> at
361 L<http://www.unicode.org/Public/MAPPINGS/VENDORS/APPLE/DEVANAGA.TXT> .
363 I believe this issue is prevalent not only for Mac Indics but also in
364 other Indic encodings, but the above were the only Indic encodings
365 maps that I could find at L<http://www.unicode.org/> .
369 =head1 Encoding vs. Charset -- terminology
371 We are used to using the term (character) I<encoding> and I<character
372 set> interchangeably. But just as confusing the terms byte and
373 character is dangerous and the terms should be differentiated when
374 needed, we need to differentiate I<encoding> and I<character set>.
376 To understand that, here is a description of how we make computers
383 First we start with which characters to include. We call this
384 collection of characters I<character repertoire>.
388 Then we have to give each character a unique ID so your computer can
389 tell the difference between 'a' and 'A'. This itemized character
390 repertoire is now a I<character set>.
394 If your computer can grow the character set without further
395 processing, you can go ahead and use it. This is called a I<coded
396 character set> (CCS) or I<raw character encoding>. ASCII is used this
401 But in many cases, especially multi-byte CJK encodings, you have to
402 tweak a little more. Your network connection may not accept any data
403 with the Most Significant Bit set, and your computer may not be able to
404 tell if a given byte is a whole character or just half of it. So you
405 have to I<encode> the character set to use it.
407 A I<character encoding scheme> (CES) determines how to encode a given
408 character set, or a set of multiple character sets. 7bit ISO-2022 is
409 an example of a CES. You switch between character sets via I<escape
414 Technically, or mathematically, speaking, a character set encoded in
415 such a CES that maps character by character may form a CCS. EUC is such
416 an example. The CES of EUC is as follows:
426 Map such a character set that consists of 94 or 96 powered by N
427 members by adding 0x80 to each byte.
431 You can also use 0x8e and 0x8f to indicate that the following sequence of
432 characters belongs to yet another character set. To each following byte
433 is added the value 0x80.
437 By carefully looking at the encoded byte sequence, you can find that the
438 byte sequence conforms a unique number. In that sense, EUC is a CCS
439 generated by a CES above from up to four CCS (complicated?). UTF-8
440 falls into this category. See L<perlUnicode/"UTF-8"> to find out how
441 UTF-8 maps Unicode to a byte sequence.
443 You may also have found out by now why 7bit ISO-2022 cannot comprise
444 a CCS. If you look at a byte sequence \x21\x21, you can't tell if
445 it is two !'s or IDEOGRAPHIC SPACE. EUC maps the latter to \xA1\xA1
446 so you have no trouble differentiating between "!!". and S<" ">.
448 =head1 Encoding Classification (by Anton Tagunov and Dan Kogai)
450 This section tries to classify the supported encodings by their
451 applicability for information exchange over the Internet and to
452 choose the most suitable aliases to name them in the context of
459 To (en|de)code encodings marked by C<(**)>, you need
460 C<Encode::HanExtra>, available from CPAN.
466 US-ASCII UTF-8 ISO-8859-* KOI8-R
467 Shift_JIS EUC-JP ISO-2022-JP ISO-2022-JP-1
470 are registered with IANA as preferred MIME names and may
471 be used over the Internet.
473 C<Shift_JIS> has been officialized by JIS X 0208:1997.
474 L<Microsoft-related naming mess> gives details.
476 C<GB2312> is the IANA name for C<EUC-CN>.
477 See L<Microsoft-related naming mess> for details.
479 C<GB_2312-80> I<raw> encoding is available as C<gb2312-raw>
480 with Encode. See L<Encode::CN> for details.
485 have not been registered with IANA (as of March 2002) but
486 seem to be supported by major web browsers.
487 The IANA name for C<EUC-CN> is C<GB2312>.
492 See L<Microsoft-related naming mess> for details.
494 C<KS_C_5601-1987> I<raw> encoding is available as C<kcs5601-raw>
495 with Encode. See L<Encode::KR> for details.
497 UTF-16 UTF-16BE UTF-16LE
499 are IANA-registered C<charset>s. See [RFC 2781] for details.
500 Jungshik Shin reports that UTF-16 with a BOM is well accepted
501 by MS IE 5/6 and NS 4/6. Beware however that
507 C<UTF-16> support in any software you're going to be
508 using/interoperating with has probably been less tested
509 then C<UTF-8> support
513 C<UTF-8> coded data seamlessly passes traditional
514 command piping (C<cat>, C<more>, etc.) while C<UTF-16> coded
515 data is likely to cause confusion (with its zero bytes,
520 it is beyond the power of words to describe the way HTML browsers
521 encode non-C<ASCII> form data. To get a general impression, visit
522 L<http://ppewww.ph.gla.ac.uk/~flavell/charset/form-i18n.html>.
523 While encoding of form data has stabilized for C<UTF-8> encoded pages
524 (at least IE 5/6, NS 6, and Opera 6 behave consistently), be sure to
525 expect fun (and cross-browser discrepancies) with C<UTF-16> encoded
530 The rule of thumb is to use C<UTF-8> unless you know what
531 you're doing and unless you really benefit from using C<UTF-16>.
537 GB 18030 (**) (see links bellow)
540 are totally valid encodings but not registered at IANA.
541 The names under which they are listed here are probably the
542 most widely-known names for these encodings and are recommended
547 is a proprietary name.
549 =head2 Microsoft-related naming mess
551 Microsoft products misuse the following names:
557 Microsoft extension to C<EUC-KR>.
559 Proper names: C<CP949>, C<UHC>, C<x-windows-949> (as used by Mozilla).
561 See L<http://lists.w3.org/Archives/Public/ietf-charsets/2001AprJun/0033.html>
564 Encode aliases C<KS_C_5601-1987> to C<cp949> to reflect this common
565 misusage. I<Raw> C<KS_C_5601-1987> encoding is available as
568 See L<Encode::KR> for details.
572 Microsoft extension to C<EUC-CN>.
574 Proper names: C<CP936>, C<GBK>.
576 C<GB2312> has been registered in the C<EUC-CN> meaning at
577 IANA. This has partially repaired the situation: Microsoft's
578 C<GB2312> has become a superset of the official C<GB2312>.
580 Encode aliases C<GB2312> to C<euc-cn> in full agreement with
581 IANA registration. C<cp936> is supported separately.
582 I<Raw> C<GB_2312-80> encoding is available as C<gb2312-raw>.
584 See L<Encode::CN> for details.
588 Microsoft extension to C<Big5>.
590 Proper name: C<CP950>.
592 Encode separately supports C<Big5> and C<cp950>.
596 Microsoft's understanding of C<Shift_JIS>.
598 JIS has not endorsed the full Microsoft standard however.
599 The official C<Shift_JIS> includes only JIS X 0201 and JIS X 0208
600 character sets, while Microsoft has always used C<Shift_JIS>
601 to encode a wider character repertoire. See C<IANA> registration for
604 As a historical predecessor, Microsoft's variant
605 probably has more rights for the name, though it may be objected
606 that Microsoft shouldn't have used JIS as part of the name
609 Unambiguous name: C<CP932>. C<IANA> name (not used?): C<Windows-31J>.
611 Encode separately supports C<Shift_JIS> and C<cp932>.
619 =item character repertoire
621 A collection of unique characters. A I<character> set in the strictest
622 sense. At this stage, characters are not numbered.
624 =item coded character set (CCS)
626 A character set that is mapped in a way computers can use directly.
627 Many character encodings, including EUC, fall in this category.
629 =item character encoding scheme (CES)
631 An algorithm to map a character set to a byte sequence. You don't
632 have to be able to tell which character set a given byte sequence
633 belongs. 7-bit ISO-2022 is a CES but it cannot be a CCS. EUC is an
634 example of being both a CCS and CES.
636 =item charset (in MIME context)
638 has long been used in the meaning of C<encoding>, CES.
640 While the word combination C<character set> has lost this meaning
641 in MIME context since [RFC 2130], the C<charset> abbreviation has
642 retained it. This is how [RFC 2277] and [RFC 2278] bless C<charset>:
644 This document uses the term "charset" to mean a set of rules for
645 mapping from a sequence of octets to a sequence of characters, such
646 as the combination of a coded character set and a character encoding
647 scheme; this is also what is used as an identifier in MIME "charset="
648 parameters, and registered in the IANA charset registry ... (Note
649 that this is NOT a term used by other standards bodies, such as ISO).
654 Extended Unix Character. See ISO-2022.
658 A CES that was carefully designed to coexist with ASCII. There are a 7
659 bit version and an 8 bit version.
661 The 7 bit version switches character set via escape sequence so it
662 cannot form a CCS. Since this is more difficult to handle in programs
663 than the 8 bit version, the 7 bit version is not very popular except for
664 iso-2022-jp, the I<de facto> standard CES for e-mails.
666 The 8 bit version can form a CCS. EUC and ISO-8859 are two examples
667 thereof. Pre-5.6 perl could use them as string literals.
671 Short for I<Universal Character Set>. When you say just UCS, it means
676 ISO/IEC 10646 encoding form: Universal Character Set coded in two
681 A character set that aims to include all character repertoires of the
682 world. Many character sets in various national as well as industrial
683 standards have become, in a way, just subsets of Unicode.
687 Short for I<Unicode Transformation Format>. Determines how to map a
688 Unicode character into a byte sequence.
692 A UTF in 16-bit encoding. Can either be in big endian or little
693 endian. The big endian version is called UTF-16BE (equal to UCS-2 +
694 surrogate support) and the little endian version is called UTF-16LE.
702 L<Encode::CN>, L<Encode::JP>, L<Encode::KR>, L<Encode::TW>,
703 L<Encode::EBCDIC>, L<Encode::Symbol>
711 European Computer Manufacturers Association
712 L<http://www.ecma.ch>
716 =item ECMA-035 (eq C<ISO-2022>)
718 L<http://www.ecma.ch/ecma1/STAND/ECMA-035.HTM>
720 The specification of ISO-2022 is available from the link above.
726 Internet Assigned Numbers Authority
727 L<http://www.iana.org/>
731 =item Assigned Charset Names by IANA
733 L<http://www.iana.org/assignments/character-sets>
735 Most of the C<canonical names> in Encode derive from this list
736 so you can directly apply the string you have extracted from MIME
737 header of mails and web pages.
743 International Organization for Standardization
744 L<http://www.iso.ch/>
748 Request For Comments -- need I say more?
749 L<http://www.rfc-editor.org/>, L<http://www.rfc.net/>,
750 L<http://www.faqs.org/rfcs/>
755 L<http://www.unicode.org/>
759 =item Unicode Glossary
761 L<http://www.unicode.org/glossary/>
763 The glossary of this document is based upon this site.
769 =head2 Other Notable Sites
775 L<http://czyborra.com/>
777 Contains a a lot of useful information, especially gory details of ISO
782 L<http://www.oreilly.com/people/authors/lunde/cjk_inf.html>
784 Somewhat obsolete (last update in 1996), but still useful. Also try
786 L<ftp://ftp.oreilly.com/pub/examples/nutshell/cjkv/pdf/GB18030_Summary.pdf>
788 You will find brief info on C<EUC-CN>, C<GBK> and mostly on C<GB 18030>.
790 =item Jungshik Shin's Hangul FAQ
792 L<http://jshin.net/faq>
794 And especially its subject 8.
796 L<http://jshin.net/faq/qa8.html>
798 A comprehensive overview of the Korean (C<KS *>) standards.
800 =item debian.org: "Introduction to i18n"
802 A brief description for most of the mentioned CJK encodings is
804 L<http://www.debian.org/doc/manuals/intro-i18n/ch-codes.en.html>
808 =head2 Offline sources
812 =item C<CJKV Information Processing> by Ken Lunde
814 CJKV Information Processing
815 1999 O'Reilly & Associates, ISBN : 1-56592-224-7
817 The modern successor of C<CJK.inf>.
819 Features a comprehensive coverage of CJKV character sets and
820 encodings along with many other issues faced by anyone trying
821 to better support CJKV languages/scripts in all the areas of
822 information processing.
824 To purchase this book, visit
825 L<http://www.oreilly.com/catalog/cjkvinfo/>
826 or your favourite bookstore.