Encode::Supported (3)
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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 MIMEname as defined inIETFRFCs. This includes all ``iso-''s.
- *
-
The name in the IANAregistry.
- *
- The name used by the organization that defined it.
In case de jure canonical names differ from that of the Encode module, they are always aliased if it ever be implemented. So you can safely tell if a given encoding is implemented or not just by passing the canonical name.
Because of all the alias issues, and because in the general case encodings have state, ``Encode'' uses an encoding object internally once an operation is in progress.
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, ``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
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.
Encode::Byte --- Extended ASCII
Encode::Byte implements most single-byte encodings except for
Symbols and - ISO-8859and 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-8859and the corresponding vendor mappings are slightly different from that ofISO.See <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.
All cp* are also available as ibm-*, ms-*, and windows-* . See also <czyborra.com/charsets/codepages.html>.
Macintosh encodings don't seem to be registered in such entities as
IANA.``Canonical'' names in Encode are based upon Apple's Tech Note 1150. See <developer.apple.com/technotes/tn/tn1150.html> for details. - KOI8 -De Facto Standard for the Cyrillic world
-
Though ISO-8859does haveISO-8859-5,theKOI8series is far more popular in the Net. Encode comes with the followingKOIcharsets. For gory details, see <czyborra.com/charsets/cyrillic.html>
---------------------------------------------------------------- koi8-f koi8-r cp878 [RFC1489] koi8-u [RFC2319] ----------------------------------------------------------------
gsm0338 - Hentai Latin 1
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/;
Note that the Encode implementation of
GSM0338does not implement the reuse of Latin capital letters as Greek capital letters (for example, the 0x5A is U+005A (LATIN CAPITAL LETTER Z), not U+0396 (GREEK CAPITAL LETTER ZETA).The
GSM0338is also covered in Encode::Byte even though it is not an ``extendedASCII''encoding.
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 '- 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 0213encodings viaCPAN
-
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, MIMEheader encoding documented inRFC 2047is 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- 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,andGB2312simultaneously, 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 11643-1and -2 which are not available in this module.CNS 11643is 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 <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 <lxr.mozilla.org/seamonkey/source/intl/uconv/ucvlatin/vps.uf> and <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
The rest which are already available are based upon the vendor mappings at <www.unicode.org/Public/MAPPINGS/VENDORS/APPLE> .
- (Mac) Indic encodings
-
The maps for the following are available at <www.unicode.org>
but remain unsupported because those encodings need an algorithmical
approach, currently unsupported by enc2xs:
MacDevanagari MacGurmukhi MacGujarati
For details, please see "Unicode mapping issues and notes:" at <www.unicode.org/Public/MAPPINGS/VENDORS/APPLE/DEVANAGA.TXT> .
I believe this issue is prevalent not only for Mac Indics but also in other Indic encodings, but the above were the only Indic encodings maps that I could find at <www.unicode.org> .
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 IDso 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.ASCIIis used this way for most cases.
- *
-
But in many cases, especially multi-byte CJKencodings, 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.
A character encoding scheme (
CES) determines how to encode a given character set, or a set of multiple character sets. 7bitISO-2022is an example of aCES.You switch between character sets via escape sequences.
Technically, or mathematically, speaking, a character set encoded in such a
- *
-
Map ASCIIunchanged.
- *
- 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.
By carefully looking at the encoded byte sequence, you can find that the byte sequence conforms a unique number. In that sense,
You may also have found out by now why 7bit
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.
Encoding names
US-ASCII UTF-8 ISO-8859-* KOI8-R Shift_JIS EUC-JP ISO-2022-JP ISO-2022-JP-1 EUC-KR Big5 GB2312
are registered with
"Shift_JIS" has been officialized by
"GB2312" is the
"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
KS_C_5601-1987
is 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-16LE
are IANA-registered "charset"s. See [
- *
- "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 HTMLbrowsers encode non-"ASCII" form data. To get a general impression, visit <www.alanflavell.org.uk/charset/form-i18n.html>. While encoding of form data has stabilized for "UTF-8" encoded pages (at leastIE 5/6, NS 6,and Opera 6 behave consistently), be sure to expect fun (and cross-browser discrepancies) with "UTF-16" encoded pages!
The rule of thumb is to use "UTF-8" unless you know what you're doing and unless you really benefit from using "UTF-16".
ISO-IR-165 [RFC1345] VISCII GB 12345 GB 18030 (**) (see links bellow) EUC-TW (**)
are totally valid encodings but not registered at
BIG5PLUS (**)
is a proprietary name.
Microsoft-related naming mess
Microsoft products misuse the following names:- KS_C_5601-1987
-
Microsoft extension to "EUC-KR".
Proper names: "CP949", "UHC", "x-windows-949" (as used by Mozilla).
See <lists.w3.org/Archives/Public/ietf-charsets/2001AprJun/0033.html> for details.
Encode aliases "KS_C_5601-1987" to "cp949" to reflect this common misusage. Raw "KS_C_5601-1987" encoding is available as "kcs5601-raw".
See Encode::KR for details.
- GB2312
-
Microsoft extension to "EUC-CN".
Proper names: "CP936", "GBK".
"GB2312" has been registered in the "EUC-CN" meaning at
IANA.This has partially repaired the situation: Microsoft's "GB2312" has become a superset of the official "GB2312".Encode aliases "GB2312" to "euc-cn" in full agreement with
IANAregistration. "cp936" is supported separately. Raw "GB_2312-80" encoding is available as "gb2312-raw".See Encode::CN for details.
- Big5
-
Microsoft extension to "Big5".
Proper name: "CP950".
Encode separately supports "Big5" and "cp950".
- Shift_JIS
-
Microsoft's understanding of "Shift_JIS".
JIShas not endorsed the full Microsoft standard however. The official "Shift_JIS" includes onlyJIS X 0201andJIS X 0208character sets, while Microsoft has always used "Shift_JIS" to encode a wider character repertoire. See "IANA" registration for "Windows-31J".
As a historical predecessor, Microsoft's variant probably has more rights for the name, though it may be objected that Microsoft shouldn't have used
JISas part of the name in the first place.Unambiguous name: "CP932". "IANA" name (also used by Mozilla, and provided as an alias by Encode): "Windows-31J".
Encode separately supports "Shift_JIS" and "cp932".
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-2022is aCESbut it cannot be aCCS. EUCis an example of being both aCCSandCES.
- charset (in MIMEcontext)
-
has long been used in the meaning of "encoding", CES.
While the word combination "character set" has lost this meaning in
MIMEcontext since [RFC 2130], the "charset" abbreviation has retained it. This is how [RFC 2277] and [RFC 2278] bless "charset":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 CESthat was carefully designed to coexist withASCII.There are a 7 bit version and an 8 bit version.
The 7 bit version switches character set via escape sequence so it cannot form a
CCS.Since this is more difficult to handle in programs than the 8 bit version, the 7 bit version is not very popular except for iso-2022-jp, the de facto standardCESfor e-mails.The 8 bit version can form a
CCS. EUCandISO-8859are two examples thereof. Pre-5.6 perl could use them as string literals. - UCS
-
Short for Universal Character Set. When you say just UCS,it means Unicode.
- UCS-2
-
ISO/IEC 10646encoding 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 UTFin 16-bit encoding. Can either be in big endian or little endian. The big endian version is calledUTF-16BE(equal toUCS-2 +surrogate support) and the little endian version is calledUTF-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
<www.ecma.ch>
-
- ECMA-035(eq ISO-2022)
-
<www.ecma.ch/ecma1/STAND/ECMA-035.HTM>
The specification of
ISO-2022is available from the link above.
-
- IANA
-
Internet Assigned Numbers Authority
<www.iana.org>
-
- Assigned Charset Names by IANA
-
<www.iana.org/assignments/character-sets>
Most of the "canonical names" in Encode derive from this list so you can directly apply the string you have extracted from
MIMEheader of mails and web pages.
- Assigned Charset Names by
-
- ISO
- International Organization for Standardization <www.iso.ch>
- RFC
- Request For Comments --- need I say more? <www.rfc-editor.org>, <www.ietf.org/rfc.html>, <www.faqs.org/rfcs>
- UC
-
Unicode Consortium
<www.unicode.org>
-
- Unicode Glossary
-
<www.unicode.org/glossary>
The glossary of this document is based upon this site.
-
Other Notable Sites
- czyborra.com
-
<czyborra.com>
Contains a lot of useful information, especially gory details of
ISOvs. vendor mappings. - CJK.inf
-
<examples.oreilly.com/cjkvinfo/doc/cjk.inf>
Somewhat obsolete (last update in 1996), but still useful. Also try
<ftp://ftp.oreilly.com/pub/examples/nutshell/cjkv/pdf/GB18030_Summary.pdf>
You will find brief info on "EUC-CN", "GBK" and mostly on "GB 18030".
- Jungshik Shin's Hangul FAQ
-
<jshin.net/faq>
And especially its subject 8.
A comprehensive overview of the Korean ("KS *") standards.
- debian.org: Introduction to i18n
-
A brief description for most of the mentioned CJKencodings is contained in <www.debian.org/doc/manuals/intro-i18n/ch-codes.en.html>
Offline sources
- CJKV Information Processing by Ken Lunde
-
CJKVInformation Processing 1999 O'Reilly & Associates,ISBN : 1-56592-224-7
The modern successor of "CJK.inf".
Features a comprehensive coverage of
CJKVcharacter sets and encodings along with many other issues faced by anyone trying to better supportCJKVlanguages/scripts in all the areas of information processing.To purchase this book, visit <oreilly.com/catalog/9780596514471> or your favourite bookstore.