Provided by: perl-doc_5.36.0-9ubuntu1.1_all 
NAME
Encode::Supported -- Encodings supported by Encode
DESCRIPTION
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.
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, "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 separately 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.
All cp* are also available as ibm-*, ms-*, and windows-* . See also
<http://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
<http://developer.apple.com/technotes/tn/tn1150.html> for details.
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/;
Note that the Encode implementation of GSM0338 does 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 GSM0338 is also covered in Encode::Byte even though it is not an "extended ASCII"
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 '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. Audrey Tang may add support for
this encoding in her 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
The rest which are already available are based upon the vendor mappings at
<http://www.unicode.org/Public/MAPPINGS/VENDORS/APPLE/> .
(Mac) Indic encodings
The maps for the following are available at <http://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
<http://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
<http://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 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.
A character encoding scheme (CES) determines how to encode a given character set, or a
set of multiple character sets. 7bit ISO-2022 is an example of a CES. You switch
between character sets via escape sequences.
Technically, or mathematically, speaking, a character set encoded in such a CES that maps
character by character may form a CCS. EUC is such an example. The CES of EUC is as
follows:
• 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.
By carefully looking at the encoded byte sequence, you can find that the byte sequence
conforms a unique number. In that sense, EUC is a CCS generated by a CES above from up to
four CCS (complicated?). UTF-8 falls into this category. See "UTF-8" in perlUnicode to
find out how UTF-8 maps Unicode to a byte sequence.
You may also have found out by now why 7bit ISO-2022 cannot comprise a CCS. If you look
at a byte sequence \x21\x21, you can't tell if it is two !'s or IDEOGRAPHIC SPACE. EUC
maps the latter to \xA1\xA1 so you have no trouble differentiating between "!!". and " ".
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 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_5601-1987
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 [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>. 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!
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 below)
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".
Proper names: "CP949", "UHC", "x-windows-949" (as used by Mozilla).
See <http://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 IANA registration. "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".
JIS has not endorsed the full Microsoft standard however. The official "Shift_JIS"
includes only JIS X 0201 and JIS X 0208 character 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 JIS as 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-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.
While the word combination "character set" has lost this meaning in MIME context 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 CES that was carefully designed to coexist with ASCII. 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 standard CES for
e-mails.
The 8 bit version can form a CCS. EUC and ISO-8859 are 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 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::Guess
References
ECMA
European Computer Manufacturers Association <http://www.ecma.ch>
ECMA-035 (eq "ISO-2022")
<http://www.ecma.ch/ecma1/STAND/ECMA-035.HTM>
The specification of ISO-2022 is available from the link above.
IANA
Internet Assigned Numbers Authority <http://www.iana.org/>
Assigned Charset Names by IANA
<http://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 MIME header of mails and web pages.
ISO
International Organization for Standardization <http://www.iso.ch/>
RFC
Request For Comments -- need I say more? <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/>
The glossary of this document is based upon this site.
Other Notable Sites
czyborra.com
<http://czyborra.com/>
Contains a lot of useful information, especially gory details of ISO vs. vendor
mappings.
CJK.inf
<http://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
<http://jshin.net/faq>
And especially its subject 8.
<http://jshin.net/faq/qa8.html>
A comprehensive overview of the Korean ("KS *") standards.
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>
Offline sources
"CJKV Information Processing" by Ken Lunde
CJKV Information Processing 1999 O'Reilly & Associates, ISBN : 1-56592-224-7
The modern successor of "CJK.inf".
Features a comprehensive coverage of CJKV character sets and encodings along with many
other issues faced by anyone trying to better support CJKV languages/scripts in all the
areas of information processing.
To purchase this book, visit <http://oreilly.com/catalog/9780596514471/> or your
favourite bookstore.