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Encode::Supported(3perl) | Perl Programmers Reference Guide | Encode::Supported(3perl) |
NAME¶
Encode::Supported -- Encodings supported by EncodeDESCRIPTION¶
Encoding Names¶
Encoding names are case insensitive. White space in names is ignored. In addition, an encoding may have aliases. Each encoding has one "canonical" name. The "canonical" name is chosen from the names of the encoding by picking the first in the following sequence (with a few exceptions).- •
- The name used by the Perl community. That includes 'utf8' and 'ascii'. Unlike aliases, canonical names directly reach the method so such frequently used words like 'utf8' don't need to do alias lookups.
- •
- The MIME name as defined in IETF RFCs. This includes all "iso-"s.
- •
- The name in the IANA registry.
- •
- The name used by the organization that defined it.
Supported Encodings¶
As of Perl 5.8.0, at least the following encodings are recognized. Note that unless otherwise specified, they are all case insensitive (via alias) and all occurrence of spaces are replaced with '-'. In other words, "ISO 8859 1" and "iso-8859-1" are identical. Encodings are categorized and implemented in several different modules but you don't have to "use Encode::XX" to make them available for most cases. Encode.pm will automatically load those modules on demand.Built-in Encodings¶
The following encodings are always available.Canonical Aliases Comments & References ---------------------------------------------------------------- ascii US-ascii ISO-646-US [ECMA] ascii-ctrl Special Encoding iso-8859-1 latin1 [ISO] null Special Encoding utf8 UTF-8 [RFC2279] ----------------------------------------------------------------null and ascii-ctrl are special. "null" fails for all character so when you set fallback mode to PERLQQ, HTMLCREF or XMLCREF, ALL CHARACTERS will fall back to character references. Ditto for "ascii-ctrl" except for control characters. For fallback modes, see Encode.
Encode::Unicode -- other Unicode encodings¶
Unicode coding schemes other than native utf8 are supported by Encode::Unicode, which will be autoloaded on demand.---------------------------------------------------------------- UCS-2BE UCS-2, iso-10646-1 [IANA, UC] UCS-2LE [UC] UTF-16 [UC] UTF-16BE [UC] UTF-16LE [UC] UTF-32 [UC] UTF-32BE UCS-4 [UC] UTF-32LE [UC] UTF-7 [RFC2152] ----------------------------------------------------------------To find how (UCS-2|UTF-(16|32))(LE|BE)? differ from one another, see Encode::Unicode. UTF-7 is a special encoding which "re-encodes" UTF-16BE into a 7-bit encoding. It is implemented seperately by Encode::Unicode::UTF7.
Encode::Byte -- Extended ASCII¶
Encode::Byte implements most single-byte encodings except for Symbols and EBCDIC. The following encodings are based on single-byte encodings implemented as extended ASCII. Most of them map \x80-\xff (upper half) to non-ASCII characters.- ISO-8859 and corresponding vendor mappings
- Since there are so many, they are presented in table format
with languages and corresponding encoding names by vendors. Note that the
table is sorted in order of ISO-8859 and the corresponding vendor mappings
are slightly different from that of ISO. See
<http://czyborra.com/charsets/iso8859.html> for details.
Lang/Regions ISO/Other Std. DOS Windows Macintosh Others ---------------------------------------------------------------- N. America (ASCII) cp437 AdobeStandardEncoding cp863 (DOSCanadaF) W. Europe iso-8859-1 cp850 cp1252 MacRoman nextstep hp-roman8 cp860 (DOSPortuguese) Cntrl. Europe iso-8859-2 cp852 cp1250 MacCentralEurRoman MacCroatian MacRomanian MacRumanian Latin3[1] iso-8859-3 Latin4[2] iso-8859-4 Cyrillics iso-8859-5 cp855 cp1251 MacCyrillic (See also next section) cp866 MacUkrainian Arabic iso-8859-6 cp864 cp1256 MacArabic cp1006 MacFarsi Greek iso-8859-7 cp737 cp1253 MacGreek cp869 (DOSGreek2) Hebrew iso-8859-8 cp862 cp1255 MacHebrew Turkish iso-8859-9 cp857 cp1254 MacTurkish Nordics iso-8859-10 cp865 cp861 MacIcelandic MacSami Thai iso-8859-11[3] cp874 MacThai (iso-8859-12 is nonexistent. Reserved for Indics?) Baltics iso-8859-13 cp775 cp1257 Celtics iso-8859-14 Latin9 [4] iso-8859-15 Latin10 iso-8859-16 Vietnamese viscii cp1258 MacVietnamese ---------------------------------------------------------------- [1] Esperanto, Maltese, and Turkish. Turkish is now on 8859-9. [2] Baltics. Now on 8859-10, except for Latvian. [3] TIS 620 + Non-Breaking Space (0xA0 / U+00A0) [4] Nicknamed Latin0; the Euro sign as well as French and Finnish letters that are missing from 8859-1 were added.
- KOI8 - De Facto Standard for the Cyrillic world
- Though ISO-8859 does have ISO-8859-5, the KOI8 series is
far more popular in the Net. Encode comes with the following KOI charsets.
For gory details, see <http://czyborra.com/charsets/cyrillic.html>
---------------------------------------------------------------- koi8-f koi8-r cp878 [RFC1489] koi8-u [RFC2319] ----------------------------------------------------------------
gsm0338 - Hentai Latin 1¶
GSM0338 is for GSM handsets. Though it shares alphanumerals with ASCII, control character ranges and other parts are mapped very differently, mainly to store Greek characters. There are also escape sequences (starting with 0x1B) to cover e.g. the Euro sign. This was once handled by Encode::Bytes but because of all those unusual specifications, Encode 2.20 has relocated the support to Encode::GSM0338. See Encode::GSM0338 for details.- gsm0338 support before 2.19
- Some special cases like a trailing 0x00 byte or a lone 0x1B
byte are not well-defined and decode() will return an empty string
for them. One possible workaround is
$gsm =~ s/\x00\z/\x00\x00/; $uni = decode("gsm0338", $gsm); $uni .= "\xA0" if $gsm =~ /\x1B\z/;
CJK: Chinese, Japanese, Korean (Multibyte)¶
Note that Vietnamese is listed above. Also read "Encoding vs Charset" below. Also note that these are implemented in distinct modules by countries, due to the size concerns (simplified Chinese is mapped to 'CN', continental China, while traditional Chinese is mapped to 'TW', Taiwan). Please refer to their respective documentation pages.- Encode::CN -- Continental China
-
Standard DOS/Win Macintosh Comment/Reference ---------------------------------------------------------------- euc-cn [1] MacChineseSimp (gbk) cp936 [2] gb12345-raw { GB12345 without CES } gb2312-raw { GB2312 without CES } hz iso-ir-165 ---------------------------------------------------------------- [1] GB2312 is aliased to this. See L<Microsoft-related naming mess> [2] gbk is aliased to this. See L<Microsoft-related naming mess>
- Encode::JP -- Japan
-
Standard DOS/Win Macintosh Comment/Reference ---------------------------------------------------------------- euc-jp shiftjis cp932 macJapanese 7bit-jis iso-2022-jp [RFC1468] iso-2022-jp-1 [RFC2237] jis0201-raw { JIS X 0201 (roman + halfwidth kana) without CES } jis0208-raw { JIS X 0208 (Kanji + fullwidth kana) without CES } jis0212-raw { JIS X 0212 (Extended Kanji) without CES } ----------------------------------------------------------------
- Encode::KR -- Korea
-
Standard DOS/Win Macintosh Comment/Reference ---------------------------------------------------------------- euc-kr MacKorean [RFC1557] cp949 [1] iso-2022-kr [RFC1557] johab [KS X 1001:1998, Annex 3] ksc5601-raw { KSC5601 without CES } ---------------------------------------------------------------- [1] ks_c_5601-1987, (x-)?windows-949, and uhc are aliased to this. See below.
- Encode::TW -- Taiwan
-
Standard DOS/Win Macintosh Comment/Reference ---------------------------------------------------------------- big5-eten cp950 MacChineseTrad {big5 aliased to big5-eten} big5-hkscs ----------------------------------------------------------------
- Encode::HanExtra -- More Chinese via CPAN
- Due to the size concerns, additional Chinese encodings
below are distributed separately on CPAN, under the name Encode::HanExtra.
Standard DOS/Win Macintosh Comment/Reference ---------------------------------------------------------------- big5ext CMEX's Big5e Extension big5plus CMEX's Big5+ Extension cccii Chinese Character Code for Information Interchange euc-tw EUC (Extended Unix Character) gb18030 GBK with Traditional Characters ----------------------------------------------------------------
- Encode::JIS2K -- JIS X 0213 encodings via CPAN
- Due to size concerns, additional Japanese encodings below
are distributed separately on CPAN, under the name Encode::JIS2K.
Standard DOS/Win Macintosh Comment/Reference ---------------------------------------------------------------- euc-jisx0213 shiftjisx0123 iso-2022-jp-3 jis0213-1-raw jis0213-2-raw ----------------------------------------------------------------
Miscellaneous encodings¶
- Encode::EBCDIC
- See perlebcdic for details.
---------------------------------------------------------------- cp37 cp500 cp875 cp1026 cp1047 posix-bc ----------------------------------------------------------------
- Encode::Symbols
- For symbols and dingbats.
---------------------------------------------------------------- symbol dingbats MacDingbats AdobeZdingbat AdobeSymbol ----------------------------------------------------------------
- Encode::MIME::Header
- Strictly speaking, MIME header encoding documented in RFC
2047 is more of encapsulation than encoding. However, their support in
modern world is imperative so they are supported.
---------------------------------------------------------------- MIME-Header [RFC2047] MIME-B [RFC2047] MIME-Q [RFC2047] ----------------------------------------------------------------
- Encode::Guess
- This one is not a name of encoding but a utility that lets you pick up the most appropriate encoding for a data out of given suspects. See Encode::Guess for details.
Unsupported encodings¶
The following encodings are not supported as yet; some because they are rarely used, some because of technical difficulties. They may be supported by external modules via CPAN in the future, however.- ISO-2022-JP-2 [RFC1554]
- Not very popular yet. Needs Unicode Database or equivalent to implement encode() (because it includes JIS X 0208/0212, KSC5601, and GB2312 simultaneously, whose code points in Unicode overlap. So you need to lookup the database to determine to what character set a given Unicode character should belong).
- ISO-2022-CN [RFC1922]
- Not very popular. Needs CNS 11643-1 and -2 which are not available in this module. CNS 11643 is supported (via euc-tw) in Encode::HanExtra. Autrijus Tang may add support for this encoding in his module in future.
- Various HP-UX encodings
- The following are unsupported due to the lack of mapping
data.
'8' - arabic8, greek8, hebrew8, kana8, thai8, and turkish8 '15' - japanese15, korean15, and roi15
- Cyrillic encoding ISO-IR-111
- Anton Tagunov doubts its usefulness.
- ISO-8859-8-1 [Hebrew]
- None of the Encode team knows Hebrew enough (ISO-8859-8, cp1255 and MacHebrew are supported because and just because there were mappings available at <http://www.unicode.org/>). Contributions welcome.
- ISIRI 3342, Iran System, ISIRI 2900 [Farsi]
- Ditto.
- Thai encoding TCVN
- Ditto.
- Vietnamese encodings VPS
- Though Jungshik Shin has reported that Mozilla supports this encoding, it was too late before 5.8.0 for us to add it. In the future, it may be available via a separate module. See <http://lxr.mozilla.org/seamonkey/source/intl/uconv/ucvlatin/vps.uf> and <http://lxr.mozilla.org/seamonkey/source/intl/uconv/ucvlatin/vps.ut> if you are interested in helping us.
- Various Mac encodings
- The following are unsupported due to the lack of mapping
data.
MacArmenian, MacBengali, MacBurmese, MacEthiopic MacExtArabic, MacGeorgian, MacKannada, MacKhmer MacLaotian, MacMalayalam, MacMongolian, MacOriya MacSinhalese, MacTamil, MacTelugu, MacTibetan MacVietnamese
- (Mac) Indic encodings
- The maps for the following are available at
<http://www.unicode.org/> but remain unsupport because those
encodings need algorithmical approach, currently unsupported by
enc2xs:
MacDevanagari MacGurmukhi MacGujarati
Encoding vs. Charset -- terminology¶
We are used to using the term (character) encoding and character set interchangeably. But just as confusing the terms byte and character is dangerous and the terms should be differentiated when needed, we need to differentiate encoding and character set. To understand that, here is a description of how we make computers grok our characters.- •
- First we start with which characters to include. We call this collection of characters character repertoire.
- •
- Then we have to give each character a unique ID so your computer can tell the difference between 'a' and 'A'. This itemized character repertoire is now a character set.
- •
- If your computer can grow the character set without further processing, you can go ahead and use it. This is called a coded character set (CCS) or raw character encoding. ASCII is used this way for most cases.
- •
- But in many cases, especially multi-byte CJK encodings, you
have to tweak a little more. Your network connection may not accept any
data with the Most Significant Bit set, and your computer may not be able
to tell if a given byte is a whole character or just half of it. So you
have to encode the character set to use it.
- •
- Map ASCII unchanged.
- •
- Map such a character set that consists of 94 or 96 powered by N members by adding 0x80 to each byte.
- •
- You can also use 0x8e and 0x8f to indicate that the following sequence of characters belongs to yet another character set. To each following byte is added the value 0x80.
Encoding Classification (by Anton Tagunov and Dan Kogai)¶
This section tries to classify the supported encodings by their applicability for information exchange over the Internet and to choose the most suitable aliases to name them in the context of such communication.- •
- To (en|de)code encodings marked by "(**)", you need "Encode::HanExtra", available from CPAN.
US-ASCII UTF-8 ISO-8859-* KOI8-R Shift_JIS EUC-JP ISO-2022-JP ISO-2022-JP-1 EUC-KR Big5 GB2312are registered with IANA as preferred MIME names and may be used over the Internet. "Shift_JIS" has been officialized by JIS X 0208:1997. "Microsoft-related naming mess" gives details. "GB2312" is the IANA name for "EUC-CN". See "Microsoft-related naming mess" for details. "GB_2312-80" raw encoding is available as "gb2312-raw" with Encode. See Encode::CN for details.
EUC-CN KOI8-U [RFC2319]have not been registered with IANA (as of March 2002) but seem to be supported by major web browsers. The IANA name for "EUC-CN" is "GB2312".
KS_C_5601-1987is heavily misused. See "Microsoft-related naming mess" for details. "KS_C_5601-1987" raw encoding is available as "kcs5601-raw" with Encode. See Encode::KR for details.
UTF-16 UTF-16BE UTF-16LEare IANA-registered "charset"s. See [RFC 2781] for details. Jungshik Shin reports that UTF-16 with a BOM is well accepted by MS IE 5/6 and NS 4/6. Beware however that
- •
- "UTF-16" support in any software you're going to be using/interoperating with has probably been less tested then "UTF-8" support
- •
- "UTF-8" coded data seamlessly passes traditional command piping ("cat", "more", etc.) while "UTF-16" coded data is likely to cause confusion (with its zero bytes, for example)
- •
- it is beyond the power of words to describe the way HTML browsers encode non-"ASCII" form data. To get a general impression, visit http://www.alanflavell.org.uk/charset/form-i18n.html <http://www.alanflavell.org.uk/charset/form-i18n.html>. While encoding of form data has stabilized for "UTF-8" encoded pages (at least IE 5/6, NS 6, and Opera 6 behave consistently), be sure to expect fun (and cross-browser discrepancies) with "UTF-16" encoded pages!
ISO-IR-165 [RFC1345] VISCII GB 12345 GB 18030 (**) (see links bellow) EUC-TW (**)are totally valid encodings but not registered at IANA. The names under which they are listed here are probably the most widely-known names for these encodings and are recommended names.
BIG5PLUS (**)is a proprietary name.
Microsoft-related naming mess¶
Microsoft products misuse the following names:- KS_C_5601-1987
- Microsoft extension to "EUC-KR".
- GB2312
- Microsoft extension to "EUC-CN".
- Big5
- Microsoft extension to "Big5".
- Shift_JIS
- Microsoft's understanding of "Shift_JIS".
Glossary¶
- character repertoire
- A collection of unique characters. A character set in the strictest sense. At this stage, characters are not numbered.
- coded character set (CCS)
- A character set that is mapped in a way computers can use directly. Many character encodings, including EUC, fall in this category.
- character encoding scheme (CES)
- An algorithm to map a character set to a byte sequence. You don't have to be able to tell which character set a given byte sequence belongs. 7-bit ISO-2022 is a CES but it cannot be a CCS. EUC is an example of being both a CCS and CES.
- charset (in MIME context)
- has long been used in the meaning of "encoding",
CES.
This document uses the term "charset" to mean a set of rules for mapping from a sequence of octets to a sequence of characters, such as the combination of a coded character set and a character encoding scheme; this is also what is used as an identifier in MIME "charset=" parameters, and registered in the IANA charset registry ... (Note that this is NOT a term used by other standards bodies, such as ISO). [RFC 2277]
- EUC
- Extended Unix Character. See ISO-2022.
- ISO-2022
- A CES that was carefully designed to coexist with ASCII.
There are a 7 bit version and an 8 bit version.
- UCS
- Short for Universal Character Set. When you say just UCS, it means Unicode.
- UCS-2
- ISO/IEC 10646 encoding form: Universal Character Set coded in two octets.
- Unicode
- A character set that aims to include all character repertoires of the world. Many character sets in various national as well as industrial standards have become, in a way, just subsets of Unicode.
- UTF
- Short for Unicode Transformation Format. Determines how to map a Unicode character into a byte sequence.
- UTF-16
- A UTF in 16-bit encoding. Can either be in big endian or little endian. The big endian version is called UTF-16BE (equal to UCS-2 + surrogate support) and the little endian version is called UTF-16LE.
See Also¶
Encode, Encode::Byte, Encode::CN, Encode::JP, Encode::KR, Encode::TW, Encode::EBCDIC, Encode::Symbol Encode::MIME::Header, Encode::GuessReferences¶
- ECMA
- European Computer Manufacturers Association <http://www.ecma.ch>
- ECMA-035 (eq "ISO-2022")
- http://www.ecma.ch/ecma1/STAND/ECMA-035.HTM
<http://www.ecma.ch/ecma1/STAND/ECMA-035.HTM>
- IANA
- Internet Assigned Numbers Authority <http://www.iana.org/>
- Assigned Charset Names by IANA
- http://www.iana.org/assignments/character-sets
<http://www.iana.org/assignments/character-sets>
- ISO
- International Organization for Standardization <http://www.iso.ch/>
- RFC
- Request For Comments -- need I say more? http://www.rfc-editor.org/ <http://www.rfc-editor.org/>, <http://www.ietf.org/rfc.html>, <http://www.faqs.org/rfcs/>
- UC
- Unicode Consortium <http://www.unicode.org/>
- Unicode Glossary
- <http://www.unicode.org/glossary/>
Other Notable Sites¶
- czyborra.com
- <http://czyborra.com/>
- CJK.inf
- <http://examples.oreilly.com/cjkvinfo/doc/cjk.inf>
- Jungshik Shin's Hangul FAQ
- <http://jshin.net/faq>
- debian.org: "Introduction to i18n"
- A brief description for most of the mentioned CJK encodings is contained in http://www.debian.org/doc/manuals/intro-i18n/ch-codes.en.html <http://www.debian.org/doc/manuals/intro-i18n/ch-codes.en.html>
Offline sources¶
- "CJKV Information Processing" by Ken Lunde
- CJKV Information Processing 1999 O'Reilly & Associates,
ISBN : 1-56592-224-7
2010-12-30 | perl v5.14.2 |