1=head1 NAME
2
3Encode::Supported -- Encodings supported by Encode
4
5=head1 DESCRIPTION
6
7=head2 Encoding Names
8
9Encoding names are case insensitive. White space in names
10is ignored.  In addition, an encoding may have aliases.
11Each encoding has one "canonical" name.  The "canonical"
12name is chosen from the names of the encoding by picking
13the first in the following sequence (with a few exceptions).
14
15=over 4
16
17=item *
18
19The name used by the Perl community.  That includes 'utf8' and 'ascii'.
20Unlike aliases, canonical names directly reach the method so such
21frequently used words like 'utf8' don't need to do alias lookups.
22
23=item *
24
25The MIME name as defined in IETF RFCs.  This includes all "iso-"s.
26
27=item *
28
29The name in the IANA registry.
30
31=item *
32
33The name used by the organization that defined it.
34
35=back
36
37In case I<de jure> canonical names differ from that of the Encode
38module, they are always aliased if it ever be implemented.  So you can
39safely tell if a given encoding is implemented or not just by passing
40the canonical name.
41
42Because of all the alias issues, and because in the general case
43encodings have state, "Encode" uses an encoding object internally
44once an operation is in progress.
45
46=head1 Supported Encodings
47
48As of Perl 5.8.0, at least the following encodings are recognized.
49Note that unless otherwise specified, they are all case insensitive
50(via alias) and all occurrence of spaces are replaced with '-'.
51In other words, "ISO 8859 1" and "iso-8859-1" are identical.
52
53Encodings are categorized and implemented in several different modules
54but you don't have to C<use Encode::XX> to make them available for
55most cases.  Encode.pm will automatically load those modules on demand.
56
57=head2 Built-in Encodings
58
59The following encodings are always available.
60
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]
66  null				                  Special Encoding
67  utf8          UTF-8                                    [RFC2279]
68  ----------------------------------------------------------------
69
70I<null> and I<ascii-ctrl> are special.  "null" fails for all character
71so when you set fallback mode to PERLQQ, HTMLCREF or XMLCREF, ALL
72CHARACTERS will fall back to character references.  Ditto for
73"ascii-ctrl" except for control characters.  For fallback modes, see
74L<Encode>.
75
76=head2 Encode::Unicode -- other Unicode encodings
77
78Unicode coding schemes other than native utf8 are supported by
79Encode::Unicode, which will be autoloaded on demand.
80
81  ----------------------------------------------------------------
82  UCS-2BE       UCS-2, iso-10646-1                      [IANA, UC]
83  UCS-2LE                                                     [UC]
84  UTF-16                                                      [UC]
85  UTF-16BE                                                    [UC]
86  UTF-16LE                                                    [UC]
87  UTF-32                                                      [UC]
88  UTF-32BE	UCS-4                                         [UC]
89  UTF-32LE                                                    [UC]
90  UTF-7                                                  [RFC2152]
91  ----------------------------------------------------------------
92
93To find how (UCS-2|UTF-(16|32))(LE|BE)? differ from one another,
94see L<Encode::Unicode>.
95
96UTF-7 is a special encoding which "re-encodes" UTF-16BE into a 7-bit
97encoding.  It is implemeneted seperately by Encode::Unicode::UTF7.
98
99=head2 Encode::Byte -- Extended ASCII
100
101Encode::Byte implements most single-byte encodings except for
102Symbols and EBCDIC. The following encodings are based on single-byte
103encodings implemented as extended ASCII.  Most of them map
104\x80-\xff (upper half) to non-ASCII characters.
105
106=over 4
107
108=item ISO-8859 and corresponding vendor mappings
109
110Since there are so many, they are presented in table format with
111languages and corresponding encoding names by vendors.  Note that
112the table is sorted in order of ISO-8859 and the corresponding vendor
113mappings are slightly different from that of ISO.  See
114L<http://czyborra.com/charsets/iso8859.html> for details.
115
116  Lang/Regions  ISO/Other Std.  DOS     Windows Macintosh  Others
117  ----------------------------------------------------------------
118  N. America    (ASCII)         cp437        AdobeStandardEncoding
119                                cp863 (DOSCanadaF)
120  W. Europe     iso-8859-1      cp850   cp1252  MacRoman  nextstep
121                                                         hp-roman8
122                                cp860 (DOSPortuguese)
123  Cntrl. Europe iso-8859-2      cp852   cp1250  MacCentralEurRoman
124                                                MacCroatian
125                                                MacRomanian
126                                                MacRumanian
127  Latin3[1]     iso-8859-3
128  Latin4[2]     iso-8859-4
129  Cyrillics     iso-8859-5      cp855   cp1251  MacCyrillic
130    (See also next section)     cp866           MacUkrainian
131  Arabic        iso-8859-6      cp864   cp1256  MacArabic
132                                cp1006          MacFarsi
133  Greek         iso-8859-7      cp737   cp1253  MacGreek
134                                cp869 (DOSGreek2)
135  Hebrew        iso-8859-8      cp862   cp1255  MacHebrew
136  Turkish       iso-8859-9      cp857   cp1254  MacTurkish
137  Nordics       iso-8859-10     cp865
138                                cp861           MacIcelandic
139                                                MacSami
140  Thai          iso-8859-11[3]  cp874           MacThai
141  (iso-8859-12 is nonexistent. Reserved for Indics?)
142  Baltics       iso-8859-13     cp775           cp1257
143  Celtics       iso-8859-14
144  Latin9 [4]    iso-8859-15
145  Latin10       iso-8859-16
146  Vietnamese    viscii                  cp1258  MacVietnamese
147  ----------------------------------------------------------------
148
149  [1] Esperanto, Maltese, and Turkish. Turkish is now on 8859-9.
150  [2] Baltics.  Now on 8859-10, except for Latvian.
151  [3] TIS 620 +  Non-Breaking Space (0xA0 / U+00A0)
152  [4] Nicknamed Latin0; the Euro sign as well as French and Finnish
153      letters that are missing from 8859-1 were added.
154
155All cp* are also available as ibm-*, ms-*, and windows-* .  See also
156L<http://czyborra.com/charsets/codepages.html>.
157
158Macintosh encodings don't seem to be registered in such entities as
159IANA.  "Canonical" names in Encode are based upon Apple's Tech Note
1601150.  See L<http://developer.apple.com/technotes/tn/tn1150.html>
161for details.
162
163=item KOI8 - De Facto Standard for the Cyrillic world
164
165Though ISO-8859 does have ISO-8859-5, the KOI8 series is far more
166popular in the Net.   L<Encode> comes with the following KOI charsets.
167For gory details, see L<http://czyborra.com/charsets/cyrillic.html>
168
169  ----------------------------------------------------------------
170  koi8-f
171  koi8-r cp878                                           [RFC1489]
172  koi8-u                                                 [RFC2319]
173  ----------------------------------------------------------------
174
175=item gsm0338 - Hentai Latin 1
176
177GSM0338 is for GSM handsets. Though it shares alphanumerals with
178ASCII, control character ranges and other parts are mapped very
179differently, mainly to store Greek characters.  There are also escape
180sequences (starting with 0x1B) to cover e.g. the Euro sign.  Some
181special cases like a trailing 0x00 byte or a lone 0x1B byte are not
182well-defined and decode() will return an empty string for them.
183One possible workaround is
184
185   $gsm =~ s/\x00\z/\x00\x00/;
186   $uni = decode("gsm0338", $gsm);
187   $uni .= "\xA0" if $gsm =~ /\x1B\z/;
188
189Note that the Encode implementation of GSM0338 does not implement the
190reuse of Latin capital letters as Greek capital letters (for example,
191the 0x5A is U+005A (LATIN CAPITAL LETTER Z), not U+0396 (GREEK CAPITAL
192LETTER ZETA).
193
194The GSM0338 is also covered in Encode::Byte even though it is not
195an "extended ASCII" encoding.
196
197=back
198
199=head2 CJK: Chinese, Japanese, Korean (Multibyte)
200
201Note that Vietnamese is listed above.  Also read "Encoding vs Charset"
202below.  Also note that these are implemented in distinct modules by
203countries, due to the size concerns (simplified Chinese is mapped
204to 'CN', continental China, while traditional Chinese is mapped to
205'TW', Taiwan).  Please refer to their respective documentation pages.
206
207=over 4
208
209=item Encode::CN -- Continental China
210
211  Standard      DOS/Win Macintosh                Comment/Reference
212  ----------------------------------------------------------------
213  euc-cn [1]            MacChineseSimp
214  (gbk)         cp936 [2]
215  gb12345-raw                      { GB12345 without CES }
216  gb2312-raw                       { GB2312  without CES }
217  hz
218  iso-ir-165
219  ----------------------------------------------------------------
220
221  [1] GB2312 is aliased to this.  See L<Microsoft-related naming mess>
222  [2] gbk is aliased to this.  See L<Microsoft-related naming mess>
223
224=item Encode::JP -- Japan
225
226  Standard      DOS/Win Macintosh                Comment/Reference
227  ----------------------------------------------------------------
228  euc-jp
229  shiftjis      cp932   macJapanese
230  7bit-jis
231  iso-2022-jp                                            [RFC1468]
232  iso-2022-jp-1                                          [RFC2237]
233  jis0201-raw  { JIS X 0201 (roman + halfwidth kana) without CES }
234  jis0208-raw  { JIS X 0208 (Kanji + fullwidth kana) without CES }
235  jis0212-raw  { JIS X 0212 (Extended Kanji)         without CES }
236  ----------------------------------------------------------------
237
238=item Encode::KR -- Korea
239
240  Standard      DOS/Win Macintosh                Comment/Reference
241  ----------------------------------------------------------------
242  euc-kr                MacKorean                        [RFC1557]
243                cp949 [1]
244  iso-2022-kr                                            [RFC1557]
245  johab                                  [KS X 1001:1998, Annex 3]
246  ksc5601-raw                              { KSC5601 without CES }
247  ----------------------------------------------------------------
248
249  [1] ks_c_5601-1987, (x-)?windows-949, and uhc are aliased to this.
250  See below.
251
252=item Encode::TW -- Taiwan
253
254  Standard      DOS/Win Macintosh                Comment/Reference
255  ----------------------------------------------------------------
256  big5-eten     cp950   MacChineseTrad {big5 aliased to big5-eten}
257  big5-hkscs
258  ----------------------------------------------------------------
259
260=item Encode::HanExtra -- More Chinese via CPAN
261
262Due to the size concerns, additional Chinese encodings below are
263distributed separately on CPAN, under the name Encode::HanExtra.
264
265  Standard      DOS/Win Macintosh                Comment/Reference
266  ----------------------------------------------------------------
267  big5ext                                   CMEX's Big5e Extension
268  big5plus                                  CMEX's Big5+ Extension
269  cccii         Chinese Character Code for Information Interchange
270  euc-tw                             EUC (Extended Unix Character)
271  gb18030                          GBK with Traditional Characters
272  ----------------------------------------------------------------
273
274=item Encode::JIS2K -- JIS X 0213 encodings via CPAN
275
276Due to size concerns, additional Japanese encodings below are
277distributed separately on CPAN, under the name Encode::JIS2K.
278
279  Standard      DOS/Win Macintosh                Comment/Reference
280  ----------------------------------------------------------------
281  euc-jisx0213
282  shiftjisx0123
283  iso-2022-jp-3
284  jis0213-1-raw
285  jis0213-2-raw
286  ----------------------------------------------------------------
287
288=back
289
290=head2 Miscellaneous encodings
291
292=over 4
293
294=item Encode::EBCDIC
295
296See L<perlebcdic> for details.
297
298  ----------------------------------------------------------------
299  cp37
300  cp500
301  cp875
302  cp1026
303  cp1047
304  posix-bc
305  ----------------------------------------------------------------
306
307=item Encode::Symbols
308
309For symbols  and dingbats.
310
311  ----------------------------------------------------------------
312  symbol
313  dingbats
314  MacDingbats
315  AdobeZdingbat
316  AdobeSymbol
317  ----------------------------------------------------------------
318
319=item Encode::MIME::Header
320
321Strictly speaking, MIME header encoding documented in RFC 2047 is more
322of encapsulation than encoding.  However, their support in modern
323world is imperative so they are supported.
324
325  ----------------------------------------------------------------
326  MIME-Header                                            [RFC2047]
327  MIME-B                                                 [RFC2047]
328  MIME-Q                                                 [RFC2047]
329  ----------------------------------------------------------------
330
331=item Encode::Guess
332
333This one is not a name of encoding but a utility that lets you pick up
334the most appropriate encoding for a data out of given I<suspects>.  See
335L<Encode::Guess> for details.
336
337=back
338
339=head1 Unsupported encodings
340
341The following encodings are not supported as yet; some because they
342are rarely used, some because of technical difficulties.  They may
343be supported by external modules via CPAN in the future, however.
344
345=over 4
346
347=item   ISO-2022-JP-2 [RFC1554]
348
349Not very popular yet.  Needs Unicode Database or equivalent to
350implement encode() (because it includes JIS X 0208/0212, KSC5601, and
351GB2312 simultaneously, whose code points in Unicode overlap.  So you
352need to lookup the database to determine to what character set a given
353Unicode character should belong).
354
355=item ISO-2022-CN [RFC1922]
356
357Not very popular.  Needs CNS 11643-1 and -2 which are not available in
358this module.  CNS 11643 is supported (via euc-tw) in Encode::HanExtra.
359Autrijus Tang may add support for this encoding in his module in future.
360
361=item Various HP-UX encodings
362
363The following are unsupported due to the lack of mapping data.
364
365  '8'  - arabic8, greek8, hebrew8, kana8, thai8, and turkish8
366  '15' - japanese15, korean15, and roi15
367
368=item Cyrillic encoding ISO-IR-111
369
370Anton Tagunov doubts its usefulness.
371
372=item ISO-8859-8-1 [Hebrew]
373
374None of the Encode team knows Hebrew enough (ISO-8859-8, cp1255 and
375MacHebrew are supported because and just because there were mappings
376available at L<http://www.unicode.org/>).  Contributions welcome.
377
378=item ISIRI 3342, Iran System, ISIRI 2900 [Farsi]
379
380Ditto.
381
382=item Thai encoding TCVN
383
384Ditto.
385
386=item Vietnamese encodings VPS
387
388Though Jungshik Shin has reported that Mozilla supports this encoding,
389it was too late before 5.8.0 for us to add it.  In the future, it
390may be available via a separate module.  See
391L<http://lxr.mozilla.org/seamonkey/source/intl/uconv/ucvlatin/vps.uf>
392and
393L<http://lxr.mozilla.org/seamonkey/source/intl/uconv/ucvlatin/vps.ut>
394if you are interested in helping us.
395
396=item Various Mac encodings
397
398The following are unsupported due to the lack of mapping data.
399
400  MacArmenian,  MacBengali,   MacBurmese,   MacEthiopic
401  MacExtArabic, MacGeorgian,  MacKannada,   MacKhmer
402  MacLaotian,   MacMalayalam, MacMongolian, MacOriya
403  MacSinhalese, MacTamil,     MacTelugu,    MacTibetan
404  MacVietnamese
405
406The rest which are already available are based upon the vendor mappings
407at L<http://www.unicode.org/Public/MAPPINGS/VENDORS/APPLE/> .
408
409=item (Mac) Indic encodings
410
411The maps for the following are available at L<http://www.unicode.org/>
412but remain unsupport because those encodings need algorithmical
413approach, currently unsupported by F<enc2xs>:
414
415  MacDevanagari
416  MacGurmukhi
417  MacGujarati
418
419For details, please see C<Unicode mapping issues and notes:> at
420L<http://www.unicode.org/Public/MAPPINGS/VENDORS/APPLE/DEVANAGA.TXT> .
421
422I believe this issue is prevalent not only for Mac Indics but also in
423other Indic encodings, but the above were the only Indic encodings
424maps that I could find at L<http://www.unicode.org/> .
425
426=back
427
428=head1 Encoding vs. Charset -- terminology
429
430We are used to using the term (character) I<encoding> and I<character
431set> interchangeably.  But just as confusing the terms byte and
432character is dangerous and the terms should be differentiated when
433needed, we need to differentiate I<encoding> and I<character set>.
434
435To understand that, here is a description of how we make computers
436grok our characters.
437
438=over 4
439
440=item *
441
442First we start with which characters to include.  We call this
443collection of characters I<character repertoire>.
444
445=item *
446
447Then we have to give each character a unique ID so your computer can
448tell the difference between 'a' and 'A'.  This itemized character
449repertoire is now a I<character set>.
450
451=item *
452
453If your computer can grow the character set without further
454processing, you can go ahead and use it.  This is called a I<coded
455character set> (CCS) or I<raw character encoding>.  ASCII is used this
456way for most cases.
457
458=item *
459
460But in many cases, especially multi-byte CJK encodings, you have to
461tweak a little more.  Your network connection may not accept any data
462with the Most Significant Bit set, and your computer may not be able to
463tell if a given byte is a whole character or just half of it.  So you
464have to I<encode> the character set to use it.
465
466A I<character encoding scheme> (CES) determines how to encode a given
467character set, or a set of multiple character sets.  7bit ISO-2022 is
468an example of a CES.  You switch between character sets via I<escape
469sequences>.
470
471=back
472
473Technically, or mathematically, speaking, a character set encoded in
474such a CES that maps character by character may form a CCS.  EUC is such
475an example.  The CES of EUC is as follows:
476
477=over 4
478
479=item *
480
481Map ASCII unchanged.
482
483=item *
484
485Map such a character set that consists of 94 or 96 powered by N
486members by adding 0x80 to each byte.
487
488=item *
489
490You can also use 0x8e and 0x8f to indicate that the following sequence of
491characters belongs to yet another character set.  To each following byte
492is added the value 0x80.
493
494=back
495
496By carefully looking at the encoded byte sequence, you can find that the
497byte sequence conforms a unique number.  In that sense, EUC is a CCS
498generated by a CES above from up to four CCS (complicated?).  UTF-8
499falls into this category.  See L<perlUnicode/"UTF-8"> to find out how
500UTF-8 maps Unicode to a byte sequence.
501
502You may also have found out by now why 7bit ISO-2022 cannot comprise
503a CCS.  If you look at a byte sequence \x21\x21, you can't tell if
504it is two !'s or IDEOGRAPHIC SPACE.  EUC maps the latter to \xA1\xA1
505so you have no trouble differentiating between "!!". and S<"  ">.
506
507=head1 Encoding Classification (by Anton Tagunov and Dan Kogai)
508
509This section tries to classify the supported encodings by their
510applicability for information exchange over the Internet and to
511choose the most suitable aliases to name them in the context of
512such communication.
513
514=over 4
515
516=item *
517
518To (en|de)code encodings marked by C<(**)>, you need
519C<Encode::HanExtra>, available from CPAN.
520
521=back
522
523Encoding names
524
525  US-ASCII    UTF-8    ISO-8859-*  KOI8-R
526  Shift_JIS   EUC-JP   ISO-2022-JP ISO-2022-JP-1
527  EUC-KR      Big5     GB2312
528
529are registered with IANA as preferred MIME names and may
530be used over the Internet.
531
532C<Shift_JIS> has been officialized by JIS X 0208:1997.
533L<Microsoft-related naming mess> gives details.
534
535C<GB2312> is the IANA name for C<EUC-CN>.
536See L<Microsoft-related naming mess> for details.
537
538C<GB_2312-80> I<raw> encoding is available as C<gb2312-raw>
539with Encode. See L<Encode::CN> for details.
540
541  EUC-CN
542  KOI8-U        [RFC2319]
543
544have not been registered with IANA (as of March 2002) but
545seem to be supported by major web browsers.
546The IANA name for C<EUC-CN> is C<GB2312>.
547
548  KS_C_5601-1987
549
550is heavily misused.
551See L<Microsoft-related naming mess> for details.
552
553C<KS_C_5601-1987> I<raw> encoding is available as C<kcs5601-raw>
554with Encode. See L<Encode::KR> for details.
555
556  UTF-16 UTF-16BE UTF-16LE
557
558are IANA-registered C<charset>s. See [RFC 2781] for details.
559Jungshik Shin reports that UTF-16 with a BOM is well accepted
560by MS IE 5/6 and NS 4/6. Beware however that
561
562=over 4
563
564=item *
565
566C<UTF-16> support in any software you're going to be
567using/interoperating with has probably been less tested
568then C<UTF-8> support
569
570=item *
571
572C<UTF-8> coded data seamlessly passes traditional
573command piping (C<cat>, C<more>, etc.) while C<UTF-16> coded
574data is likely to cause confusion (with its zero bytes,
575for example)
576
577=item *
578
579it is beyond the power of words to describe the way HTML browsers
580encode non-C<ASCII> form data. To get a general impression, visit
581L<http://ppewww.ph.gla.ac.uk/~flavell/charset/form-i18n.html>.
582While encoding of form data has stabilized for C<UTF-8> encoded pages
583(at least IE 5/6, NS 6, and Opera 6 behave consistently), be sure to
584expect fun (and cross-browser discrepancies) with C<UTF-16> encoded
585pages!
586
587=back
588
589The rule of thumb is to use C<UTF-8> unless you know what
590you're doing and unless you really benefit from using C<UTF-16>.
591
592  ISO-IR-165    [RFC1345]
593  VISCII
594  GB 12345
595  GB 18030 (**)  (see links bellow)
596  EUC-TW   (**)
597
598are totally valid encodings but not registered at IANA.
599The names under which they are listed here are probably the
600most widely-known names for these encodings and are recommended
601names.
602
603  BIG5PLUS (**)
604
605is a proprietary name.
606
607=head2 Microsoft-related naming mess
608
609Microsoft products misuse the following names:
610
611=over 4
612
613=item KS_C_5601-1987
614
615Microsoft extension to C<EUC-KR>.
616
617Proper names: C<CP949>, C<UHC>, C<x-windows-949> (as used by Mozilla).
618
619See L<http://lists.w3.org/Archives/Public/ietf-charsets/2001AprJun/0033.html>
620for details.
621
622Encode aliases C<KS_C_5601-1987> to C<cp949> to reflect this common
623misusage. I<Raw> C<KS_C_5601-1987> encoding is available as
624C<kcs5601-raw>.
625
626See L<Encode::KR> for details.
627
628=item GB2312
629
630Microsoft extension to C<EUC-CN>.
631
632Proper names: C<CP936>, C<GBK>.
633
634C<GB2312> has been registered in the C<EUC-CN> meaning at
635IANA. This has partially repaired the situation: Microsoft's
636C<GB2312> has become a superset of the official C<GB2312>.
637
638Encode aliases C<GB2312> to C<euc-cn> in full agreement with
639IANA registration. C<cp936> is supported separately.
640I<Raw> C<GB_2312-80> encoding is available as C<gb2312-raw>.
641
642See L<Encode::CN> for details.
643
644=item Big5
645
646Microsoft extension to C<Big5>.
647
648Proper name: C<CP950>.
649
650Encode separately supports C<Big5> and C<cp950>.
651
652=item Shift_JIS
653
654Microsoft's understanding of C<Shift_JIS>.
655
656JIS has not endorsed the full Microsoft standard however.
657The official C<Shift_JIS> includes only JIS X 0201 and JIS X 0208
658character sets, while Microsoft has always used C<Shift_JIS>
659to encode a wider character repertoire. See C<IANA> registration for
660C<Windows-31J>.
661
662As a historical predecessor, Microsoft's variant
663probably has more rights for the name, though it may be objected
664that Microsoft shouldn't have used JIS as part of the name
665in the first place.
666
667Unambiguous name: C<CP932>. C<IANA> name (not used?): C<Windows-31J>.
668
669Encode separately supports C<Shift_JIS> and C<cp932>.
670
671=back
672
673=head1 Glossary
674
675=over 4
676
677=item character repertoire
678
679A collection of unique characters.  A I<character> set in the strictest
680sense. At this stage, characters are not numbered.
681
682=item coded character set (CCS)
683
684A character set that is mapped in a way computers can use directly.
685Many character encodings, including EUC, fall in this category.
686
687=item character encoding scheme (CES)
688
689An algorithm to map a character set to a byte sequence.  You don't
690have to be able to tell which character set a given byte sequence
691belongs.  7-bit ISO-2022 is a CES but it cannot be a CCS.  EUC is an
692example of being both a CCS and CES.
693
694=item charset (in MIME context)
695
696has long been used in the meaning of C<encoding>, CES.
697
698While the word combination C<character set> has lost this meaning
699in MIME context since [RFC 2130], the C<charset> abbreviation has
700retained it. This is how [RFC 2277] and [RFC 2278] bless C<charset>:
701
702 This document uses the term "charset" to mean a set of rules for
703 mapping from a sequence of octets to a sequence of characters, such
704 as the combination of a coded character set and a character encoding
705 scheme; this is also what is used as an identifier in MIME "charset="
706 parameters, and registered in the IANA charset registry ...  (Note
707 that this is NOT a term used by other standards bodies, such as ISO).
708 [RFC 2277]
709
710=item EUC
711
712Extended Unix Character.  See ISO-2022.
713
714=item ISO-2022
715
716A CES that was carefully designed to coexist with ASCII.  There are a 7
717bit version and an 8 bit version.
718
719The 7 bit version switches character set via escape sequence so it
720cannot form a CCS.  Since this is more difficult to handle in programs
721than the 8 bit version, the 7 bit version is not very popular except for
722iso-2022-jp, the I<de facto> standard CES for e-mails.
723
724The 8 bit version can form a CCS.  EUC and ISO-8859 are two examples
725thereof.  Pre-5.6 perl could use them as string literals.
726
727=item UCS
728
729Short for I<Universal Character Set>.  When you say just UCS, it means
730I<Unicode>.
731
732=item UCS-2
733
734ISO/IEC 10646 encoding form: Universal Character Set coded in two
735octets.
736
737=item Unicode
738
739A character set that aims to include all character repertoires of the
740world.  Many character sets in various national as well as industrial
741standards have become, in a way, just subsets of Unicode.
742
743=item UTF
744
745Short for I<Unicode Transformation Format>.  Determines how to map a
746Unicode character into a byte sequence.
747
748=item UTF-16
749
750A UTF in 16-bit encoding.  Can either be in big endian or little
751endian.  The big endian version is called UTF-16BE (equal to UCS-2 +
752surrogate support) and the little endian version is called UTF-16LE.
753
754=back
755
756=head1 See Also
757
758L<Encode>,
759L<Encode::Byte>,
760L<Encode::CN>, L<Encode::JP>, L<Encode::KR>, L<Encode::TW>,
761L<Encode::EBCDIC>, L<Encode::Symbol>
762L<Encode::MIME::Header>, L<Encode::Guess>
763
764=head1 References
765
766=over 4
767
768=item ECMA
769
770European Computer Manufacturers Association
771L<http://www.ecma.ch>
772
773=over 4
774
775=item ECMA-035 (eq C<ISO-2022>)
776
777L<http://www.ecma.ch/ecma1/STAND/ECMA-035.HTM>
778
779The specification of ISO-2022 is available from the link above.
780
781=back
782
783=item IANA
784
785Internet Assigned Numbers Authority
786L<http://www.iana.org/>
787
788=over 4
789
790=item Assigned Charset Names by IANA
791
792L<http://www.iana.org/assignments/character-sets>
793
794Most of the C<canonical names> in Encode derive from this list
795so you can directly apply the string you have extracted from MIME
796header of mails and web pages.
797
798=back
799
800=item ISO
801
802International Organization for Standardization
803L<http://www.iso.ch/>
804
805=item RFC
806
807Request For Comments -- need I say more?
808L<http://www.rfc-editor.org/>, L<http://www.rfc.net/>,
809L<http://www.faqs.org/rfcs/>
810
811=item UC
812
813Unicode Consortium
814L<http://www.unicode.org/>
815
816=over 4
817
818=item Unicode Glossary
819
820L<http://www.unicode.org/glossary/>
821
822The glossary of this document is based upon this site.
823
824=back
825
826=back
827
828=head2 Other Notable Sites
829
830=over 4
831
832=item czyborra.com
833
834L<http://czyborra.com/>
835
836Contains a a lot of useful information, especially gory details of ISO
837vs. vendor mappings.
838
839=item CJK.inf
840
841L<http://www.oreilly.com/people/authors/lunde/cjk_inf.html>
842
843Somewhat obsolete (last update in 1996), but still useful.  Also try
844
845L<ftp://ftp.oreilly.com/pub/examples/nutshell/cjkv/pdf/GB18030_Summary.pdf>
846
847You will find brief info on C<EUC-CN>, C<GBK> and mostly on C<GB 18030>.
848
849=item Jungshik Shin's Hangul FAQ
850
851L<http://jshin.net/faq>
852
853And especially its subject 8.
854
855L<http://jshin.net/faq/qa8.html>
856
857A comprehensive overview of the Korean (C<KS *>) standards.
858
859=item debian.org: "Introduction to i18n"
860
861A brief description for most of the mentioned CJK encodings is
862contained in
863L<http://www.debian.org/doc/manuals/intro-i18n/ch-codes.en.html>
864
865=back
866
867=head2 Offline sources
868
869=over 4
870
871=item C<CJKV Information Processing> by Ken Lunde
872
873CJKV Information Processing
8741999 O'Reilly & Associates, ISBN : 1-56592-224-7
875
876The modern successor of C<CJK.inf>.
877
878Features a comprehensive coverage of CJKV character sets and
879encodings along with many other issues faced by anyone trying
880to better support CJKV languages/scripts in all the areas of
881information processing.
882
883To purchase this book, visit
884L<http://www.oreilly.com/catalog/cjkvinfo/>
885or your favourite bookstore.
886
887=back
888
889=cut
890