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🏷️ NAME

Encode::Supported — Encodings supported by Encode

🚀 Quick Reference

Use Case	Command	Description
Encode a string to UTF-8	use Encode; $utf8 = encode('UTF-8', $string);	Converts $string to UTF-8
Decode from UTF-8	use Encode; $string = decode('UTF-8', $utf8);	Converts UTF-8 bytes back to Perl string
List all supported encodings	use Encode; @encodings = Encode->encodings();	Returns list of all encoding names
Find encoding alias	Encode::resolve_alias('latin1');	Returns canonical name 'iso-8859-1'
Detect encoding from data	Encode::Guess->guess($data);	Attempts to guess encoding from suspects
Encode for MIME header	encode('MIME-Header', $subject);	Encodes string for email headers (RFC 2047)

📖 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

Encode::Unicode

Unicode coding schemes other than native utf8 are supported by Encode::Unicode, which will be autoloaded on demand.

Canonical	Aliases	References
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

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, cp866	cp1251	MacCyrillic, MacUkrainian
Arabic	iso-8859-6	cp864, cp1006	cp1256	MacArabic, MacFarsi
Greek	iso-8859-7	cp737, cp869 (DOSGreek2)	cp1253	MacGreek
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
Baltics	iso-8859-13	cp775	cp1257
Celtics	iso-8859-14
Latin9 [4]	iso-8859-15
Latin10	iso-8859-16
Vietnamese	viscii		cp1258	MacVietnamese

1. [1] Esperanto, Maltese, and Turkish. Turkish is now on 8859-9.
2. [2] Baltics. Now on 8859-10, except for Latvian.
3. [3] TIS 620 + Non-Breaking Space (0xA0 / U+00A0)
4. [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

Canonical	Aliases	References
koi8-f
koi8-r	cp878	RFC1489
koi8-u		RFC2319

📱 GSM 0338 - 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

Encode::CN

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. [1] GB2312 is aliased to this. See Microsoft-related naming mess
2. [2] gbk is aliased to this. See Microsoft-related naming mess

🇯🇵 Encode::JP — Japan

Encode::JP

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

Encode::KR

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. [1] ks_c_5601-1987, (x-)?windows-949, and uhc are aliased to this. See below.

🇹🇼 Encode::TW — Taiwan

Encode::TW

Standard	DOS/Win	Macintosh	Comment/Reference
big5-eten	cp950	MacChineseTrad	{big5 aliased to big5-eten}
big5-hkscs

🇨🇳 Encode::HanExtra — More Chinese via CPAN

Encode::HanExtra

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

Encode::JIS2K

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

Encode::EBCDIC

See perlebcdic for details.

Encoding
cp37
cp500
cp875
cp1026
cp1047
posix-bc

🔣 Encode::Symbols

Encode::Symbols

For symbols and dingbats.

Encoding
symbol
dingbats
MacDingbats
AdobeZdingbat
AdobeSymbol

📧 Encode::MIME::Header

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.

Encoding	Reference
MIME-Header	RFC2047
MIME-B	RFC2047
MIME-Q	RFC2047

🔮 Encode::Guess

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().
• ISO-2022-CN [RFC1922] — Not very popular. Needs CNS 11643-1 and -2.
• Various HP-UX encodings — '8' (arabic8, greek8, hebrew8, kana8, thai8, turkish8) and '15' (japanese15, korean15, roi15) unsupported due to lack of mapping data.
• ISO-IR-111 — Cyrillic encoding, usefulness doubted.
• ISO-8859-8-1 (Hebrew) — Not enough knowledge among Encode team.
• ISIRI 3342, Iran System, ISIRI 2900 (Farsi) — Ditto.
• Thai encoding TCVN — Ditto.
• Vietnamese encodings VPS — Ditto.
• Various Mac encodings — MacArmenian, MacBengali, MacBurmese, MacEthiopic, MacExtArabic, MacGeorgian, MacKannada, MacKhmer, MacLaotian, MacMalayalam, MacMongolian, MacOriya, MacSinhalese, MacTamil, MacTelugu, MacTibetan, MacVietnamese.
• (Mac) Indic encodings — MacDevanagari, MacGurmukhi, MacGujarati (need algorithmical approach).

📐 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, 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

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 than "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 (**), 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". 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
• IANA — Internet Assigned Numbers Authority http://www.iana.org/. Assigned Charset Names by IANA http://www.iana.org/assignments/character-sets
• ISO — International Organization for Standardization http://www.iso.ch/
• RFC — Request For Comments 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/ — 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
• Jungshik Shin's Hangul FAQ — http://jshin.net/faq, especially subject 8: http://jshin.net/faq/qa8.html
• debian.org: "Introduction to i18n" — 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. To purchase this book, visit http://oreilly.com/catalog/9780596514471/ or your favourite bookstore.

🏷️ NAME 🚀 Quick Reference 📖 DESCRIPTION 🔗 See Also 📚 References