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Unicode

January 01, 1970

Unicode, formally The Unicode Standard,[note 1] is a text encoding standard maintained by the Unicode Consortium designed to support the use of text written in all of the world's major writing systems. Version 15.1 of the standard[A] defines 149813 characters[3] and 161 scripts used in various ordinary, literary, academic, and technical contexts.

Unicode
Logo of the Unicode Consortium
Alias(es)
Language(s)See list of scripts
StandardUnicode Standard
Encoding formats
(uncommon)
(obsolete)
Preceded by
  • Official website
  • Technical website
This article contains uncommon Unicode characters. Without proper rendering support, you may see question marks, boxes, or other symbols.

Many common characters, including numerals, punctuation, and other symbols, are unified within the standard and are not treated as specific to any given writing system. Unicode encodes thousands of emoji, with the continued development thereof conducted by the Consortium as a part of the standard.[4] Moreover, the widespread adoption of Unicode was in large part responsible for the initial popularization of emoji outside of Japan. Unicode is ultimately capable of encoding more than 1.1 million characters.

Unicode has largely supplanted the previous environment of myriad incompatible character sets, each used within different locales and on different computer architectures. Unicode is used to encode the vast majority of text on the Internet, including most web pages, and relevant Unicode support has become a common consideration in contemporary software development.

The Unicode character repertoire is synchronized with ISO/IEC 10646, each being code-for-code identical with one another. However, The Unicode Standard is more than just a repertoire within which characters are assigned. To aid developers and designers, the standard also provides charts and reference data, as well as annexes explaining concepts germane to various scripts, providing guidance for their implementation. Topics covered by these annexes include character normalization, character composition and decomposition, collation, and directionality.[5]

Unicode text is processed and stored as binary data using one of several encodings, which define how to translate the standard's abstracted codes for characters into sequences of bytes. The Unicode Standard itself defines three encodings: UTF-8, UTF-16, and UTF-32, though several others exist. Of these, UTF-8 is the most widely used by a large margin, in part due to its backwards-compatibility with ASCII.

Origin and development edit

Unicode was originally designed with the intent of transcending limitations present in all text encodings designed up to that point: each encoding was relied upon for use in its own context, but with no particular expectation of compatibility with any other. Indeed, any two encodings chosen were often totally unworkable when used together, with text encoded in one interpreted as garbage characters by the other. Most encodings had only been designed to facilitate interoperation between a handful of scripts—often primarily between a given script and Latin characters—not between a large number of scripts, and not with all of the scripts supported being treated in a consistent manner.

The philosophy that underpins Unicode seeks to encode the underlying characters—graphemes and grapheme-like units—rather than graphical distinctions considered mere variant glyphs thereof, that are instead best handled by the typeface, through the use of markup, or by some other means. In particularly complex cases, such as the treatment of orthographical variants in Han characters, there is considerable disagreement regarding which differences justify their own encodings, and which are only graphical variants of other characters.

At the most abstract level, Unicode assigns a unique number called a code point to each character. Many issues of visual representation—including size, shape, and style—are intended to be up to the discretion of the software actually rendering the text, such as a web browser or word processor. However, partially with the intent of encouraging rapid adoption, the simplicity of this original model has become somewhat more elaborate over time, and various pragmatic concessions have been made over the course of the standard's development.

The first 256 code points mirror the ISO/IEC 8859-1 standard, with the intent of trivializing the conversion of text already written in Western European scripts. To preserve the distinctions made by different legacy encodings, therefore allowing for conversion between them and Unicode without any loss of information, many characters nearly identical to others, in both appearance and intended function, were given distinct code points. For example, the Halfwidth and Fullwidth Forms block encompasses a full semantic duplicate of the Latin alphabet, because legacy CJK encodings contained both "fullwidth" (matching the width of CJK characters) and "halfwidth" (matching ordinary Latin script) characters.

The Unicode Bulldog Award is given to people deemed to be influential in Unicode's development, with recipients including Tatsuo Kobayashi, Thomas Milo, Roozbeh Pournader, Ken Lunde, and Michael Everson.[6]

History edit

The origins of Unicode can be traced back to the 1980s, to a group of individuals with connections to Xerox's Character Code Standard (XCCS).[7] In 1987, Xerox employee Joe Becker, along with Apple employees Lee Collins and Mark Davis, started investigating the practicalities of creating a universal character set.[8] With additional input from Peter Fenwick and Dave Opstad,[7] Becker published a draft proposal for an "international/multilingual text character encoding system in August 1988, tentatively called Unicode". He explained that "the name 'Unicode' is intended to suggest a unique, unified, universal encoding".[7]

In this document, entitled Unicode 88, Becker outlined a scheme using 16-bit characters:[7]

Unicode is intended to address the need for a workable, reliable world text encoding. Unicode could be roughly described as "wide-body ASCII" that has been stretched to 16 bits to encompass the characters of all the world's living languages. In a properly engineered design, 16 bits per character are more than sufficient for this purpose.

This design decision was made based on the assumption that only scripts and characters in "modern" use would require encoding:[7]

Unicode gives higher priority to ensuring utility for the future than to preserving past antiquities. Unicode aims in the first instance at the characters published in the modern text (e.g. in the union of all newspapers and magazines printed in the world in 1988), whose number is undoubtedly far below 214 = 16,384. Beyond those modern-use characters, all others may be defined to be obsolete or rare; these are better candidates for private-use registration than for congesting the public list of generally useful Unicode.

In early 1989, the Unicode working group expanded to include Ken Whistler and Mike Kernaghan of Metaphor, Karen Smith-Yoshimura and Joan Aliprand of Research Libraries Group, and Glenn Wright of Sun Microsystems. In 1990, Michel Suignard and Asmus Freytag of Microsoft and NeXT's Rick McGowan had also joined the group. By the end of 1990, most of the work of remapping existing standards had been completed, and a final review draft of Unicode was ready.

The Unicode Consortium was incorporated in California on 3 January 1991,[9] and the first volume of The Unicode Standard was published that October. The second volume, now adding Han ideographs, was published in June 1992.

In 1996, a surrogate character mechanism was implemented in Unicode 2.0, so that Unicode was no longer restricted to 16 bits. This increased the Unicode codespace to over a million code points, which allowed for the encoding of many historic scripts, such as Egyptian hieroglyphs, and thousands of rarely used or obsolete characters that had not been anticipated for inclusion in the standard. Among these characters are various rarely used CJK characters—many mainly being used in proper names, making them far more necessary for a universal encoding than the original Unicode architecture envisioned.[10]

Version 1.0 of Microsoft's TrueType specification, published in 1992, used the name "Apple Unicode" instead of "Unicode" for the Platform ID in the naming table.

Unicode Consortium edit

Main article: Unicode Consortium

The Unicode Consortium is a nonprofit organization that coordinates Unicode's development. Full members include most of the main computer software and hardware companies (and few others) with any interest in text-processing standards, including Adobe, Apple, Google, IBM, Meta (previously as Facebook), Microsoft, Netflix, and SAP.[11]

Over the years several countries or government agencies have been members of the Unicode Consortium. Presently only the Ministry of Endowments and Religious Affairs (Oman) is a full member with voting rights.[11]

The Consortium has the ambitious goal of eventually replacing existing character encoding schemes with Unicode and its standard Unicode Transformation Format (UTF) schemes, as many of the existing schemes are limited in size and scope and are incompatible with multilingual environments.

Scripts covered edit

Main article: Script (Unicode)
 
Many modern applications can render a substantial subset of the many scripts in Unicode, as demonstrated by this screenshot from the OpenOffice.org application.

Unicode currently covers most major writing systems in use today.[12][better source needed]

As of 2024, a total of 161 scripts[13] are included in the latest version of Unicode (covering alphabets, abugidas and syllabaries), although there are still scripts that are not yet encoded, particularly those mainly used in historical, liturgical, and academic contexts. Further additions of characters to the already encoded scripts, as well as symbols, in particular for mathematics and music (in the form of notes and rhythmic symbols), also occur.

The Unicode Roadmap Committee (Michael Everson, Rick McGowan, Ken Whistler, V.S. Umamaheswaran)[14] maintain the list of scripts that are candidates or potential candidates for encoding and their tentative code block assignments on the Unicode Roadmap[15] page of the Unicode Consortium website. For some scripts on the Roadmap, such as Jurchen and Khitan large script, encoding proposals have been made and they are working their way through the approval process. For other scripts, such as Numidian and Rongorongo, no proposal has yet been made, and they await agreement on character repertoire and other details from the user communities involved.

Some modern invented scripts which have not yet been included in Unicode (e.g., Tengwar) or which do not qualify for inclusion in Unicode due to lack of real-world use (e.g., Klingon) are listed in the ConScript Unicode Registry, along with unofficial but widely used Private Use Areas code assignments.

There is also a Medieval Unicode Font Initiative focused on special Latin medieval characters. Part of these proposals has been already included in Unicode.

Script Encoding Initiative edit

The Script Encoding Initiative,[16] a project run by Deborah Anderson at the University of California, Berkeley was founded in 2002 with the goal of funding proposals for scripts not yet encoded in the standard. The project has become a major source of proposed additions to the standard in recent years.[17]

Versions edit

The Unicode Consortium together with the ISO have developed a shared repertoire following the initial publication of The Unicode Standard: Unicode and the ISO's Universal Coded Character Set (UCS) use identical character names and code points. However, the Unicode versions do differ from their ISO equivalents in two significant ways.

While the UCS is a simple character map, Unicode specifies the rules, algorithms, and properties necessary to achieve interoperability between different platforms and languages. Thus, The Unicode Standard includes more information, covering in-depth topics such as bitwise encoding, collation, and rendering. It also provides a comprehensive catalog of character properties, including those needed for supporting bidirectional text, as well as visual charts and reference data sets to aid implementers. Previously, The Unicode Standard was sold as a print volume containing the complete core specification, standard annexes,[note 2] and code charts. However, version 5.0, published in 2006, was the last version printed this way. Starting with version 5.2, only the core specification, published as a print-on-demand paperback, may be purchased.[18] The full text, on the other hand, is published as a free PDF on the Unicode website.

A practical reason for this publication method highlights the second significant difference between the UCS and Unicode—the frequency with which updated versions are released and new characters added. The Unicode Standard has regularly released annual expanded versions, occasionally with more than one version released in a calendar year and with rare cases where the scheduled release had to be postponed. For instance, in April 2020, a month after version 13.0 was published, the Unicode Consortium announced they had changed the intended release date for version 14.0, pushing it back six months to September 2021 due to the COVID-19 pandemic.

Unicode 15.1, the latest version, was released on 12 September 2023. It is a minor version update to version 15.0—released on 13 September 2022—which added a total of 4,489 new characters, including two new scripts, an extension to the CJK Unified Ideographs block, and multiple additions to existing blocks. 33 new emoji were added, such as the "wireless" (network) symbol and additional colored hearts.[19][20]

Thus far, the following versions of The Unicode Standard have been published. Update versions, which do not include any changes to character repertoire, are signified by the third number (e.g., "version 4.0.1") and are omitted in the table below.[21]

Unicode version history and notable changes to characters and scripts
Version Date Book UCS edition Total Details
Scripts Characters[a]
1.0.0[22] October 1991 ISBN 0-201-56788-1
(vol. 1)
 — 24 7129 Initial scripts covered: Arabic, Armenian, Bengali, Bopomofo, Cyrillic, Devanagari, Georgian, Greek and Coptic, Gujarati, Gurmukhi, Hangul, Hebrew, Hiragana, Kannada, Katakana, Lao, Latin, Malayalam, Odia, Tamil, Telugu, Thai, and Tibetan
1.0.1[23] June 1992 ISBN 0-201-60845-6
(vol. 2)
 25 28327+21204
−6 		The initial 20,902 CJK Unified Ideographs
1.1[24] June 1993 — ISO/IEC 10646-1:1993

[b]

24 34168+5963
−9 		33 reclassified as control characters. 4,306 Hangul syllables, Tibetan removed
2.0[25] July 1996 ISBN 0-201-48345-9 25 38885+11373
−6656 		Original set of Hangul syllables removed, new set of 11,172 Hangul syllables added at new location, Tibetan added back in a new location and with a different character repertoire, Surrogate character mechanism defined, Plane 15 and Plane 16 Private Use Areas allocated
2.1[26] May 1998 — 38887+2
 		U+20AC € EURO SIGN, U+FFFC  OBJECT REPLACEMENT CHARACTER[26]
3.0[27] September 1999 ISBN 0-201-61633-5 ISO/IEC 10646-1:2000 38 49194+10307
 		Cherokee, Geʽez, Khmer, Mongolian, Burmese, Ogham, runes, Sinhala, Syriac, Thaana, Canadian Aboriginal syllabics, and Yi Syllables, Braille patterns
3.1[28] March 2001 — ISO/IEC 10646-1:2000[c]
ISO/IEC 10646-2:2001 		41 94140+44946
 		Deseret, Gothic and Old Italic, sets of symbols for Western and Byzantine music, 42,711 additional CJK Unified Ideographs
3.2[29] March 2002 45 95156+1016
 		Philippine scripts (Buhid, Hanunoo, Tagalog, and Tagbanwa)
4.0[30] April 2003 ISBN 0-321-18578-1 ISO/IEC 10646:2003

[d]

52 96382+1226
 		Cypriot syllabary, Limbu, Linear B, Osmanya, Shavian, Tai Le, and Ugaritic, Hexagram symbols
4.1[31] March 2005 — 59 97655+1273
 		Buginese, Glagolitic, Kharosthi, New Tai Lue, Old Persian, Sylheti Nagri, and Tifinagh, Coptic disunified from Greek, ancient Greek numbers and musical symbols First named character sequences were introduced.[32]
5.0 July 2006 ISBN 0-321-48091-0 64 99024+1369
 		Balinese, cuneiform, N'Ko, ʼPhags-pa, Phoenician[33]
5.1[34] April 2008 — 75 100648+1624
 		Carian, Cham, Kayah Li, Lepcha, Lycian, Lydian, Ol Chiki, Rejang, Saurashtra, Sundanese, and Vai, sets of symbols for the Phaistos Disc, Mahjong tiles, Domino tiles, additions to Burmese, Scribal abbreviations, U+1E9E ẞ LATIN CAPITAL LETTER SHARP S
5.2[35] October 2009 ISBN 978-1-936213-00-9 90 107296+6648
 		Avestan, Bamum, Gardiner's sign list of Egyptian hieroglyphs, Imperial Aramaic, Inscriptional Pahlavi, Inscriptional Parthian, Javanese, Kaithi, Lisu, Meetei Mayek, Old South Arabian, Old Turkic, Samaritan, Tai Tham and Tai Viet, additional CJK Unified Ideographs, Jamo for Old Hangul, Vedic Sanskrit
6.0[36] October 2010 ISBN 978-1-936213-01-6 ISO/IEC 10646:2010

[e]

93 109384+2088
 		Batak, Brahmi, Mandaic, playing card symbols, transport and map symbols, alchemical symbols, emoticons and emoji,[37] additional CJK Unified Ideographs
6.1[38] January 2012 ISBN 978-1-936213-02-3 ISO/IEC 10646:2012

[f]

100 110116+732
 		Chakma, Meroitic cursive, Meroitic hieroglyphs, Miao, Sharada, Sora Sompeng, and Takri
6.2[39] September 2012 ISBN 978-1-936213-07-8 110117+1
 		U+20BA ₺ TURKISH LIRA SIGN
6.3[40] September 2013 ISBN 978-1-936213-08-5 110122+5
 		5 bidirectional formatting characters
7.0[41] June 2014 ISBN 978-1-936213-09-2 123 112956+2834
 		Bassa Vah, Caucasian Albanian, Duployan, Elbasan, Grantha, Khojki, Khudawadi, Linear A, Mahajani, Manichaean, Mende Kikakui, Modi, Mro, Nabataean, Old North Arabian, Old Permic, Pahawh Hmong, Palmyrene, Pau Cin Hau, Psalter Pahlavi, Siddham, Tirhuta, Warang Citi, and dingbats
8.0[42] June 2015 ISBN 978-1-936213-10-8 ISO/IEC 10646:2014

[g]

129 120672+7716
 		Ahom, Anatolian hieroglyphs, Hatran, Multani, Old Hungarian, SignWriting, additional CJK Unified Ideographs, lowercase letters for Cherokee, 5 emoji skin tone modifiers
9.0[45] June 2016 ISBN 978-1-936213-13-9 135 128172+7500
 		Adlam, Bhaiksuki, Marchen, Newa, Osage, Tangut, 72 emoji[46]
10.0[47] June 2017 ISBN 978-1-936213-16-0 ISO/IEC 10646:2017

[h]

139 136690+8518
 		Zanabazar Square, Soyombo, Masaram Gondi, Nüshu, hentaigana, 7,494 CJK Unified Ideographs, 56 emoji, bitcoin symbol
11.0[48] June 2018 ISBN 978-1-936213-19-1 146 137374+684
 		Dogra, Georgian Mtavruli capital letters, Gunjala Gondi, Hanifi Rohingya, Indic Siyaq Numbers, Makasar, Medefaidrin, Old Sogdian and Sogdian, Maya numerals, 5 CJK Unified Ideographs, symbols for xiangqi and star ratings, 145 emoji
12.0[49] March 2019 ISBN 978-1-936213-22-1 150 137928+554
 		Elymaic, Nandinagari, Nyiakeng Puachue Hmong, Wancho, Miao script, hiragana and katakana small letters, Tamil historic fractions and symbols, Lao letters for Pali, Latin letters for Egyptological and Ugaritic transliteration, hieroglyph format controls, 61 emoji
12.1[50] May 2019 ISBN 978-1-936213-25-2 137929+1
 		U+32FF ㋿ SQUARE ERA NAME REIWA
13.0[51] March 2020 ISBN 978-1-936213-26-9 ISO/IEC 10646:2020

[52]

154 143859+5930
 		Chorasmian, Dhives Akuru, Khitan small script, Yezidi, 4,969 CJK ideographs, Arabic script additions used to write Hausa, Wolof, and other African languages, additions used to write Hindko and Punjabi in Pakistan, Bopomofo additions used for Cantonese, Creative Commons license symbols, graphic characters for compatibility with teletext and home computer systems, 55 emoji
14.0[53] September 2021 ISBN 978-1-936213-29-0 159 144697+838
 		Toto, Cypro-Minoan, Vithkuqi, Old Uyghur, Tangsa, extended IPA, Arabic script additions for use in languages across Africa and in Iran, Pakistan, Malaysia, Indonesia, Java, and Bosnia, additions for honorifics and Quranic use, additions to support languages in North America, the Philippines, India, and Mongolia, U+20C0 ⃀ SOM SIGN, Znamenny musical notation, 37 emoji
15.0[54] September 2022 ISBN 978-1-936213-32-0 161 149186+4489
 		Kawi and Mundari, 20 emoji, 4,192 CJK ideographs, control characters for Egyptian hieroglyphs
15.1[55] September 2023 ISBN 978-1-936213-33-7 149813+627
 		Additional CJK ideographs
  1. ^ The total number of graphic and format characters, excluding private-use characters, control characters, noncharacters, and surrogate code points).
  2. ^
    • 2.0 added Amendments 5, 6, and 7
    • 2.1 added two characters from Amendment 18.
  3. ^ 3.2 added Amendment 1.
  4. ^
    • 4.1 added Amendment 1
    • 5.0 added Amendment 2 as well as four characters from Amendment 3
    • 5.1 added Amendment 4
    • 5.2 added Amendments 5 and 6
  5. ^ Plus the Indian rupee sign
  6. ^
  7. ^ Plus Amendment 1, as well as the Lari sign, nine CJK unified ideographs, and 41 emoji;[43]
    9.0 added Amendment 2, as well as Adlam, Newa, Japanese TV symbols, and 74 emoji and symbols.[44]
  8. ^
    • Plus 56 emoji, 285 hentaigana characters, and 3 Zanabazar Square characters
    • 11.0 added 46 Mtavruli Georgian capital letters, 5 CJK unified ideographs, and 66 emoji
    • 12.0 added 62 additional characters.

Projected versions edit

The Unicode Consortium normally releases a new version of The Unicode Standard once a year, or occasionally twice a year. Version 16.0, the next major version, is scheduled to be published in 2024, and is projected to include six new scripts (Todhri, Sunuwar, Gurung Khema, Kirat Rai, Garay, and Ol Onal), additional Burmese numerals for Shan and Mon alphabets, additional symbols for legacy computing, and at least six new emoji.[56][57]

Architecture and terminology edit

See also: Universal Character Set characters

Codespace and code points edit

The Unicode Standard defines a codespace:[58] a sequence of integers called code points[59] in the range from 0 to 1114111, notated according to the standard as U+0000–U+10FFFF.[60] The codespace is a systematic, architecture-independent representation of The Unicode Standard; actual text is processed as binary data via one of several Unicode encodings, such as UTF-8.

In this normative notation, the two-character prefix U+ always precedes a written code point,[61] and the code points themselves are written as hexadecimal numbers. At least four hexadecimal digits are always written, with leading zeros prepended as needed. For example, the code point U+00F7 ÷ DIVISION SIGN is padded with two leading zeros, but U+13254 𓉔 EGYPTIAN HIEROGLYPH O004 ( ) is not padded.[62]

There are a total of 220 + (216 − 211) = 1112064 valid code points within the codespace. (This number arises from the limitations of the UTF-16 character encoding, which can encode the 216 code points in the range U+0000 through U+FFFF except for the 211 code points in the range U+D800 through U+DFFF, which are used as surrogate pairs to encode the 220 code points in the range U+10000 through U+10FFFF.)

Code planes and blocks edit

Main article: Plane (Unicode)

The Unicode codespace is divided into 17 planes, numbered 0 to 16. Plane 0 is the Basic Multilingual Plane (BMP), and contains the most commonly used characters. All code points in the BMP are accessed as a single code unit in UTF-16 encoding and can be encoded in one, two or three bytes in UTF-8. Code points in planes 1 through 16 (the supplementary planes) are accessed as surrogate pairs in UTF-16 and encoded in four bytes in UTF-8.

Within each plane, characters are allocated within named blocks of related characters. The size of a block is always a multiple of 16, and is often a multiple of 128, but is otherwise arbitrary. Characters required for a given script may be spread out over several different, potentially disjunct blocks within the codespace.

General Category property edit

Each code point is assigned a classification, listed as the code point's General Category property. Here, at the uppermost level code points are categorized as one of Letter, Mark, Number, Punctuation, Symbol, Separator, or Other. Under each category, each code point is then further subcategorized. In most cases, other properties must be used to adequately describe all the characteristics of any given code point.

General Category (Unicode Character Property)[a]
Value Category Major, minor Basic type[b] Character assigned[b] Count[c]
(as of 15.1)		 Remarks
 
L, Letter; LC, Cased Letter (Lu, Ll, and Lt only)[d]
Lu Letter, uppercase Graphic Character 1,831
Ll Letter, lowercase Graphic Character 2,233
Lt Letter, titlecase Graphic Character 31 Ligatures or digraphs containing an uppercase followed by a lowercase part (e.g., Dž, Lj, Nj, and Dz)
Lm Letter, modifier Graphic Character 397 A modifier letter
Lo Letter, other Graphic Character 132,234 An ideograph or a letter in a unicase alphabet
M, Mark
Mn Mark, nonspacing Graphic Character 1,985
Mc Mark, spacing combining Graphic Character 452
Me Mark, enclosing Graphic Character 13
N, Number
Nd Number, decimal digit Graphic Character 680 All these, and only these, have Numeric Type = De[e]
Nl Number, letter Graphic Character 236 Numerals composed of letters or letterlike symbols (e.g., Roman numerals)
No Number, other Graphic Character 915 E.g., vulgar fractions, superscript and subscript digits
P, Punctuation
Pc Punctuation, connector Graphic Character 10 Includes spacing underscore characters such as "_", and other spacing tie characters. Unlike other punctuation characters, these may be classified as "word" characters by regular expression libraries.[f]
Pd Punctuation, dash Graphic Character 26 Includes several hyphen characters
Ps Punctuation, open Graphic Character 79 Opening bracket characters
Pe Punctuation, close Graphic Character 77 Closing bracket characters
Pi Punctuation, initial quote Graphic Character 12 Opening quotation mark. Does not include the ASCII "neutral" quotation mark. May behave like Ps or Pe depending on usage
Pf Punctuation, final quote Graphic Character 10 Closing quotation mark. May behave like Ps or Pe depending on usage
Po Punctuation, other Graphic Character 628
S, Symbol
Sm Symbol, math Graphic Character 948 Mathematical symbols (e.g., +, −, =, ×, ÷, √, ∊, ≠). Does not include parentheses and brackets, which are in categories Ps and Pe. Also does not include !, *, -, or /, which despite frequent use as mathematical operators, are primarily considered to be "punctuation".
Sc Symbol, currency Graphic Character 63 Currency symbols
Sk Symbol, modifier Graphic Character 125
So Symbol, other Graphic Character 6,639
Z, Separator
Zs Separator, space Graphic Character 17 Includes the space, but not TAB, CR, or LF, which are Cc
Zl Separator, line Format Character 1 Only U+2028 LINE SEPARATOR (LSEP)
Zp Separator, paragraph Format Character 1 Only U+2029 PARAGRAPH SEPARATOR (PSEP)
C, Other
Cc Other, control Control Character 65 (will never change)[e] No name,[g] <control>
Cf Other, format Format Character 170 Includes the soft hyphen, joining control characters (ZWNJ and ZWJ), control characters to support bidirectional text, and language tag characters
Cs Other, surrogate Surrogate Not (only used in UTF-16) 2,048 (will never change)[e] No name,[g] <surrogate>
Co Other, private use Private-use Character (but no interpretation specified) 137,468 total (will never change)[e] (6,400 in BMP, 131,068 in Planes 15–16) No name,[g] <private-use>
Cn Other, not assigned Noncharacter Not 66 (will not change unless the range of Unicode code points is expanded)[e] No name,[g] <noncharacter>
Reserved Not 824,652 No name,[g] <reserved>
  1. ^ "Table 4-4: General Category" (PDF). The Unicode Standard. Unicode Consortium. September 2022.
  2. ^ a b "Table 2-3: Types of code points" (PDF). The Unicode Standard. Unicode Consortium. September 2022.
  3. ^ "DerivedGeneralCategory.txt". The Unicode Consortium. 2022-04-26.
  4. ^ "5.7.1 General Category Values". UTR #44: Unicode Character Database. Unicode Consortium. 2020-03-04.
  5. ^ a b c d e Unicode Character Encoding Stability Policies: Property Value Stability Stability policy: Some gc groups will never change. gc=Nd corresponds with Numeric Type=De (decimal).
  6. ^ "Annex C: Compatibility Properties (§ word)". Unicode Regular Expressions. Version 23. Unicode Consortium. 2022-02-08. Unicode Technical Standard #18.
  7. ^ a b c d e "Table 4-9: Construction of Code Point Labels" (PDF). The Unicode Standard. Unicode Consortium. September 2022. A Code Point Label may be used to identify a nameless code point. E.g. <control-hhhh>, <control-0088>. The Name remains blank, which can prevent inadvertently replacing, in documentation, a Control Name with a true Control code. Unicode also uses <not a character> for <noncharacter>.

The 1024 points in the range U+D800–U+DBFF are known as high-surrogate code points, and code points in the range U+DC00–U+DFFF (1024 code points) are known as low-surrogate code points. A high-surrogate code point followed by a low-surrogate code point forms a surrogate pair in UTF-16 in order to represent code points greater than U+FFFF. In principle, these code points cannot otherwise be used, though in practice this rule is often ignored, especially when not using UTF-16.

A small set of code points are guaranteed never to be assigned to characters, although third-parties may make independent use of them at their discretion. There are 66 of these noncharacters: U+FDD0–U+FDEF and the last two code points in each of the 17 planes (e.g. U+FFFE, U+FFFF, U+1FFFE, U+1FFFF, ..., U+10FFFE, U+10FFFF). The set of noncharacters is stable, and no new noncharacters will ever be defined.[63] Like surrogates, the rule that these cannot be used is often ignored, although the operation of the byte order mark assumes that U+FFFE will never be the first code point in a text. The exclusion of surrogates and noncharacters leaves 1111998 code points available for use.

Private-use code points are considered to be assigned, but they intentionally have no interpretation specified by The Unicode Standard[64] such that any interchange of such code points requires an independent agreement between the sender and receiver as to their interpretation. There are three private-use areas in the Unicode codespace:

  • Private Use Area: U+E000–U+F8FF (6400 characters),
  • Supplementary Private Use Area-A: U+F0000–U+FFFFD (65534 characters),
  • Supplementary Private Use Area-B: U+100000–U+10FFFD (65534 characters).

Graphic characters are those defined by The Unicode Standard to have particular semantics, either having a visible glyph shape or representing a visible space. As of Unicode 15.1, there are 149641 graphic characters.

Format characters are characters that do not have a visible appearance but may have an effect on the appearance or behavior of neighboring characters. For example, U+200C ZERO WIDTH NON-JOINER and U+200D ZERO WIDTH JOINER may be used to change the default shaping behavior of adjacent characters (e.g. to inhibit ligatures or request ligature formation). There are 172 format characters in Unicode 15.1.

65 code points, the ranges U+0000–U+001F and U+007F–U+009F, are reserved as control codes, corresponding to the C0 and C1 control codes as defined in ISO/IEC 6429. U+0089 LINE TABULATION, U+008A LINE FEED, and U+000D CARRIAGE RETURN are widely used in texts using Unicode. In a phenomenon known as mojibake, the C1 code points are improperly decoded according to the Windows-1252 codepage, previously widely used in Western European contexts.

Together, graphic, format, control code, and private use characters are collectively referred to as assigned characters. Reserved code points are those code points that are valid and available for use, but have not yet been assigned. As of Unicode 15.1, there are 824652 reserved code points.

Abstract characters edit

Further information: Universal Character Set characters § Characters, grapheme clusters and glyphs

The set of graphic and format characters defined by Unicode does not correspond directly to the repertoire of abstract characters representable under Unicode. Unicode encodes characters by associating an abstract character with a particular code point.[65] However, not all abstract characters are encoded as a single Unicode character, and some abstract characters may be represented in Unicode by a sequence of two or more characters. For example, a Latin small letter "i" with an ogonek, a dot above, and an acute accent, which is required in Lithuanian, is represented by the character sequence U+012F; U+0307; U+0301. Unicode maintains a list of uniquely named character sequences for abstract characters that are not directly encoded in Unicode.[66]

All assigned characters have a unique and immutable name by which they are identified. This immutability has been guaranteed since version 2.0 of The Unicode Standard by its Name Stability policy.[63] In cases where a name is seriously defective and misleading, or has a serious typographical error, a formal alias may be defined that applications are encouraged to use in place of the official character name. For example, U+A015 ꀕ YI SYLLABLE WU has the formal alias YI SYLLABLE ITERATION MARK, and U+FE18 ︘ PRESENTATION FORM FOR VERTICAL RIGHT WHITE LENTICULAR BRAKCET (sic) has the formal alias PRESENTATION FORM FOR VERTICAL RIGHT WHITE LENTICULAR BRACKET.[67]

Ready-made versus composite characters edit

Unicode includes a mechanism for modifying characters that greatly extends the supported repertoire of glyphs. This covers the use of combining diacritical marks that may be added after the base character by the user. Multiple combining diacritics may be simultaneously applied to the same character. Unicode also contains precomposed versions of most letter/diacritic combinations in normal use. These make the conversion to and from legacy encodings simpler, and allow applications to use Unicode as an internal text format without having to implement combining characters. For example, é can be represented in Unicode as U+0065 e LATIN SMALL LETTER E followed by U+0301 ◌́ COMBINING ACUTE ACCENT), and equivalently as the precomposed character U+00E9 é LATIN SMALL LETTER E WITH ACUTE. Thus, users often have multiple equivalent ways of encoding the same character. The mechanism of canonical equivalence within The Unicode Standard ensures the practical interchangeability of these equivalent encodings.

An example of this arises with the Korean alphabet Hangul: Unicode provides a mechanism for composing Hangul syllables from their individual Hangul Jamo subcomponents. However, it also provides 11172 combinations of precomposed syllables made from the most common jamo.

CJK characters presently only have codes for uncomposable radicals and precomposed forms. Most Han characters have either been intentionally composed from, or reconstructed as compositions of, simpler orthographic elements called radicals, so in principle Unicode could have enabled their composition as it did with Hangul. While this could have greatly reduced the number of required code points, as well as allowing the algorithmic synthesis of many arbitrary new characters, the complexities of character etymologies and the post-hoc nature of radical systems add immense complexity to the proposal. Indeed, attempts to design CJK encodings on the basis of composing radicals have been met with difficulties resulting from the reality that Chinese characters do not decompose as simply or as regularly as Hangul does.

The CJK Radicals Supplement block is assigned to the range U+2E80–U+2EFF, and the Kangxi radicals are assigned to U+2F00–U+2FDF. The Ideographic Description Sequences block covers the range U+2FF0–U+2FFB, but The Unicode Standard warns against using its characters as an alternate representation for characters encoded elsewhere:

This process is different from a formal encoding of an ideograph. There is no canonical description of unencoded ideographs; there is no semantic assigned to described ideographs; there is no equivalence defined for described ideographs. Conceptually, ideographic descriptions are more akin to the English phrase "an 'e' with an acute accent on it" than to the character sequence <U+0065, U+0301>.

Ligatures edit

 
The Devanāgarī ddhrya-ligature (द् + ध् + र् + य = द्ध्र्य) of JanaSanskritSans[68]
 
The Arabic lām-alif ligature (ل ‎+‎ ا ‎=‎ لا)

Many scripts, including Arabic and Devanāgarī, have special orthographic rules that require certain combinations of letterforms to be combined into special ligature forms. The rules governing ligature formation can be quite complex, requiring special script-shaping technologies such as ACE (Arabic Calligraphic Engine by DecoType in the 1980s and used to generate all the Arabic examples in the printed editions of The Unicode Standard), which became the proof of concept for OpenType (by Adobe and Microsoft), Graphite (by SIL International), or AAT (by Apple).

Instructions are also embedded in fonts to tell the operating system how to properly output different character sequences. A simple solution to the placement of combining marks or diacritics is assigning the marks a width of zero and placing the glyph itself to the left or right of the left sidebearing (depending on the direction of the script they are intended to be used with). A mark handled this way will appear over whatever character precedes it, but will not adjust its position relative to the width or height of the base glyph; it may be visually awkward and it may overlap some glyphs. Real stacking is impossible but can be approximated in limited cases (for example, Thai top-combining vowels and tone marks can just be at different heights to start with). Generally, this approach is only effective in monospaced fonts but may be used as a fallback rendering method when more complex methods fail.

Standardized subsets edit

Several subsets of Unicode are standardized: Microsoft Windows since Windows NT 4.0 supports WGL-4 with 657 characters, which is considered to support all contemporary European languages using the Latin, Greek, or Cyrillic script. Other standardized subsets of Unicode include the Multilingual European Subsets:[69] MES-1 (Latin scripts only, 335 characters), MES-2 (Latin, Greek, and Cyrillic 1062 characters)[70] and MES-3A & MES-3B (two larger subsets, not shown here). MES-2 includes every character in MES-1 and WGL-4.

The standard DIN 91379[71] specifies a subset of Unicode letters, special characters, and sequences of letters and diacritic signs to allow the correct representation of names and to simplify data exchange in Europe. This standard supports all of the official languages of all European Union countries, as well as the German minority languages and the official languages of Iceland, Liechtenstein, Norway, and Switzerland. To allow the transliteration of names in other writing systems to the Latin script according to the relevant ISO standards, all necessary combinations of base letters and diacritic signs are provided.

WGL-4, MES-1 and MES-2
Row Cells Range(s)
00 20–7E Basic Latin (00–7F)
A0–FF Latin-1 Supplement (80–FF)
01 00–13, 14–15, 16–2B, 2C–2D, 2E–4D, 4E–4F, 50–7E, 7F Latin Extended-A (00–7F)
8F, 92, B7, DE-EF, FA–FF Latin Extended-B (80–FF ...)
02 18–1B, 1E–1F Latin Extended-B (... 00–4F)
59, 7C, 92 IPA Extensions (50–AF)
BB–BD, C6, C7, C9, D6, D8–DB, DC, DD, DF, EE Spacing Modifier Letters (B0–FF)
03 74–75, 7A, 7E, 84–8A, 8C, 8E–A1, A3–CE, D7, DA–E1 Greek (70–FF)
04 00–5F, 90–91, 92–C4, C7–C8, CB–CC, D0–EB, EE–F5, F8–F9 Cyrillic (00–FF)
1E 02–03, 0A–0B, 1E–1F, 40–41, 56–57, 60–61, 6A–6B, 80–85, 9B, F2–F3 Latin Extended Additional (00–FF)
1F 00–15, 18–1D, 20–45, 48–4D, 50–57, 59, 5B, 5D, 5F–7D, 80–B4, B6–C4, C6–D3, D6–DB, DD–EF, F2–F4, F6–FE Greek Extended (00–FF)
20 13–14, 15, 17, 18–19, 1A–1B, 1C–1D, 1E, 20–22, 26, 30, 32–33, 39–3A, 3C, 3E, 44, 4A General Punctuation (00–6F)
7F, 82 Superscripts and Subscripts (70–9F)
A3–A4, A7, AC, AF Currency Symbols (A0–CF)
21 05, 13, 16, 22, 26, 2E Letterlike Symbols (00–4F)
5B–5E Number Forms (50–8F)
90–93, 94–95, A8 Arrows (90–FF)
22 00, 02, 03, 06, 08–09, 0F, 11–12, 15, 19–1A, 1E–1F, 27–28, 29, 2A, 2B, 48, 59, 60–61, 64–65, 82–83, 95, 97 Mathematical Operators (00–FF)
23 02, 0A, 20–21, 29–2A Miscellaneous Technical (00–FF)
25 00, 02, 0C, 10, 14, 18, 1C, 24, 2C, 34, 3C, 50–6C Box Drawing (00–7F)
80, 84, 88, 8C, 90–93 Block Elements (80–9F)
A0–A1, AA–AC, B2, BA, BC, C4, CA–CB, CF, D8–D9, E6 Geometric Shapes (A0–FF)
26 3A–3C, 40, 42, 60, 63, 65–66, 6A, 6B Miscellaneous Symbols (00–FF)
F0 (01–02) Private Use Area (00–FF ...)
FB 01–02 Alphabetic Presentation Forms (00–4F)
FF FD Specials

Rendering software that cannot process a Unicode character appropriately often displays it as an open rectangle, or as U+FFFD to indicate the position of the unrecognized character. Some systems have made attempts to provide more information about such characters. Apple's Last Resort font will display a substitute glyph indicating the Unicode range of the character, and the SIL International's Unicode fallback font will display a box showing the hexadecimal scalar value of the character.

Mapping and encodings edit

Several mechanisms have been specified for storing a series of code points as a series of bytes.

Unicode defines two mapping methods: the Unicode Transformation Format (UTF) encodings, and the Universal Coded Character Set (UCS) encodings. An encoding maps (possibly a subset of) the range of Unicode code points to sequences of values in some fixed-size range, termed code units. All UTF encodings map code points to a unique sequence of bytes.[72] The numbers in the names of the encodings indicate the number of bits per code unit (for UTF encodings) or the number of bytes per code unit (for UCS encodings and UTF-1). UTF-8 and UTF-16 are the most commonly used encodings. UCS-2 is an obsolete subset of UTF-16; UCS-4 and UTF-32 are functionally equivalent.

UTF encodings include:

  • UTF-8, which uses one to four bytes per code point, and has maximal compatibility with ASCII
  • UTF-16, which uses either one or two 16-bit units per code point, but cannot encode surrogates
  • UTF-32, which uses one 32-bit unit per code point
  • UTF-EBCDIC, not specified as part of The Unicode Standard, which uses one to five bytes per code point, intended to maximize compatibility with EBCDIC

UTF-8 uses one to four bytes per code point and, being compact for Latin scripts and ASCII-compatible, provides the de facto standard encoding for the interchange of Unicode text. It is used by FreeBSD and most recent Linux distributions as a direct replacement for legacy encodings in general text handling.

The UCS-2 and UTF-16 encodings specify the Unicode byte order mark (BOM) for use at the beginnings of text files, which may be used for byte-order detection (or byte endianness detection). The BOM, encoded as U+FEFF ZERO WIDTH NO-BREAK SPACE, has the important property of unambiguity on byte reorder, regardless of the Unicode encoding used; U+FFFE (the result of byte-swapping U+FEFF) does not equate to a legal character, and U+FEFF in places other than the beginning of text conveys the zero-width non-break space.

The same character converted to UTF-8 becomes the byte sequence EF BB BF. The Unicode Standard allows the BOM "can serve as a signature for UTF-8 encoded text where the character set is unmarked".[73] Some software developers have adopted it for other encodings, including UTF-8, in an attempt to distinguish UTF-8 from local 8-bit code pages. However RFC 3629, the UTF-8 standard, recommends that byte order marks be forbidden in protocols using UTF-8, but discusses the cases where this may not be possible. In addition, the large restriction on possible patterns in UTF-8 (for instance there cannot be any lone bytes with the high bit set) means that it should be possible to distinguish UTF-8 from other character encodings without relying on the BOM.

In UTF-32 and UCS-4, one 32-bit code unit serves as a fairly direct representation of any character's code point (although the endianness, which varies across different platforms, affects how the code unit manifests as a byte sequence). In the other encodings, each code point may be represented by a variable number of code units. UTF-32 is widely used as an internal representation of text in programs (as opposed to stored or transmitted text), since every Unix operating system that uses the gcc compilers to generate software uses it as the standard "wide character" encoding. Some programming languages, such as Seed7, use UTF-32 as an internal representation for strings and characters. Recent versions of the Python programming language (beginning with 2.2) may also be configured to use UTF-32 as the representation for Unicode strings, effectively disseminating such encoding in high-level coded software.

Punycode, another encoding form, enables the encoding of Unicode strings into the limited character set supported by the ASCII-based Domain Name System (DNS). The encoding is used as part of IDNA, which is a system enabling the use of Internationalized Domain Names in all scripts that are supported by Unicode. Earlier and now historical proposals include UTF-5 and UTF-6.

GB18030 is another encoding form for Unicode, from the Standardization Administration of China. It is the official character set of the People's Republic of China (PRC). BOCU-1 and SCSU are Unicode compression schemes. The April Fools' Day RFC of 2005 specified two parody UTF encodings, UTF-9 and UTF-18.

Adoption edit

See also: UTF-8 § Adoption

Unicode, in the form of UTF-8, has been the most common encoding for the World Wide Web since 2008.[74] It has near-universal adoption, and much of the non-UTF-8 content is found in other Unicode encodings, e.g. UTF-16. As of 2024, UTF-8 accounts for on average 97.8% of all web pages (and 987 of the top 1,000 highest-ranked web pages).[75] Although many pages only use ASCII characters to display content, UTF-8 was designed with 8-bit ASCII as a subset and almost no websites now declare their encoding to only be ASCII instead of UTF-8.[76] Over a third of the languages tracked have 100% UTF-8 use.

All internet protocols maintained by Internet Engineering Task Force, e.g. FTP,[77] have required support for UTF-8 since the publication of RFC 2277 in 1998, which specified that all IETF protocols "MUST be able to use the UTF-8 charset".[78]

Operating systems edit

Unicode has become the dominant scheme for the internal processing and storage of text. Although a great deal of text is still stored in legacy encodings, Unicode is used almost exclusively for building new information processing systems. Early adopters tended to use UCS-2 (the fixed-length two-byte obsolete precursor to UTF-16) and later moved to UTF-16 (the variable-length current standard), as this was the least disruptive way to add support for non-BMP characters. The best known such system is Windows NT (and its descendants, 2000, XP, Vista, 7, 8, 10, and 11), which uses UTF-16 as the sole internal character encoding. The Java and .NET bytecode environments, macOS, and KDE also use it for internal representation. Partial support for Unicode can be installed on Windows 9x through the Microsoft Layer for Unicode.

UTF-8 (originally developed for Plan 9)[79] has become the main storage encoding on most Unix-like operating systems (though others are also used by some libraries) because it is a relatively easy replacement for traditional extended ASCII character sets. UTF-8 is also the most common Unicode encoding used in HTML documents on the World Wide Web.

Multilingual text-rendering engines which use Unicode include Uniscribe and DirectWrite for Microsoft Windows, ATSUI and Core Text for macOS, and Pango for GTK+ and the GNOME desktop.

Input methods edit

Main article: Unicode input

Because keyboard layouts cannot have simple key combinations for all characters, several operating systems provide alternative input methods that allow access to the entire repertoire.

ISO/IEC 14755,[80] which standardises methods for entering Unicode characters from their code points, specifies several methods. There is the Basic method, where a beginning sequence is followed by the hexadecimal representation of the code point and the ending sequence. There is also a screen-selection entry method specified, where the characters are listed in a table on a screen, such as with a character map program.

Online tools for finding the code point for a known character include Unicode Lookup[81] by Jonathan Hedley and Shapecatcher[82] by Benjamin Milde. In Unicode Lookup, one enters a search key (e.g. "fractions"), and a list of corresponding characters with their code points is returned. In Shapecatcher, based on Shape context, one draws the character in a box and a list of characters approximating the drawing, with their code points, is returned.

Email edit

Main article: Unicode and email

MIME defines two different mechanisms for encoding non-ASCII characters in email, depending on whether the characters are in email headers (such as the "Subject:"), or in the text body of the message; in both cases, the original character set is identified as well as a transfer encoding. For email transmission of Unicode, the UTF-8 character set and the Base64 or the Quoted-printable transfer encoding are recommended, depending on whether much of the message consists of ASCII characters. The details of the two different mechanisms are specified in the MIME standards and generally are hidden from users of email software.

The IETF has defined[83][84] a framework for internationalized email using UTF-8, and has updated[85][86][87][88] several protocols in accordance with that framework.

The adoption of Unicode in email has been very slow.[citation needed] Some East Asian text is still encoded in encodings such as ISO-2022, and some devices, such as mobile phones,[citation needed] still cannot correctly handle Unicode data. Support has been improving, however. Many major free mail providers such as Yahoo! Mail, Gmail, and Outlook.com support it.

Web edit

Main article: Unicode and HTML

All W3C recommendations have used Unicode as their document character set since HTML 4.0. Web browsers have supported Unicode, especially UTF-8, for many years. There used to be display problems resulting primarily from font related issues; e.g. v6 and older of Microsoft Internet Explorer did not render many code points unless explicitly told to use a font that contains them.[89]

Although syntax rules may affect the order in which characters are allowed to appear, XML (including XHTML) documents, by definition,[90] comprise characters from most of the Unicode code points, with the exception of:

  • FFFE or FFFF.
  • most of the C0 control codes,
  • the permanently unassigned code points D800–DFFF,

HTML characters manifest either directly as bytes according to the document's encoding, if the encoding supports them, or users may write them as numeric character references based on the character's Unicode code point. For example, the references &#916;, &#1049;, &#1511;, &#1605;, &#3671;, &#12354;, &#21494;, &#33865;, and &#47568; (or the same numeric values expressed in hexadecimal, with &#x as the prefix) should display on all browsers as Δ, Й, ק ,م, ๗, あ, 叶, 葉, and 말.

When specifying URIs, for example as URLs in HTTP requests, non-ASCII characters must be percent-encoded.

Fonts edit

Main article: Unicode font

Unicode is not in principle concerned with fonts per se, seeing them as implementation choices.[91] Any given character may have many allographs, from the more common bold, italic and base letterforms to complex decorative styles. A font is "Unicode compliant" if the glyphs in the font can be accessed using code points defined in The Unicode Standard.[92] The standard does not specify a minimum number of characters that must be included in the font; some fonts have quite a small repertoire.

Free and retail fonts based on Unicode are widely available, since TrueType and OpenType support Unicode (and Web Open Font Format (WOFF and WOFF2) is based on those). These font formats map Unicode code points to glyphs, but OpenType and TrueType font files are restricted to 65,535 glyphs. Collection files provide a "gap mode" mechanism for overcoming this limit in a single font file. (Each font within the collection still has the 65,535 limit, however.) A TrueType Collection file would typically have a file extension of ".ttc".

Thousands of fonts exist on the market, but fewer than a dozen fonts—sometimes described as "pan-Unicode" fonts—attempt to support the majority of Unicode's character repertoire. Instead, Unicode-based fonts typically focus on supporting only basic ASCII and particular scripts or sets of characters or symbols. Several reasons justify this approach: applications and documents rarely need to render characters from more than one or two writing systems; fonts tend to demand resources in computing environments; and operating systems and applications show increasing intelligence in regard to obtaining glyph information from separate font files as needed, i.e., font substitution. Furthermore, designing a consistent set of rendering instructions for tens of thousands of glyphs constitutes a monumental task; such a venture passes the point of diminishing returns for most typefaces.

Newlines edit

Unicode partially addresses the newline problem that occurs when trying to read a text file on different platforms. Unicode defines a large number of characters that conforming applications should recognize as line terminators.

In terms of the newline, Unicode introduced U+2028 LINE SEPARATOR and U+2029 PARAGRAPH SEPARATOR. This was an attempt to provide a Unicode solution to encoding paragraphs and lines semantically, potentially replacing all of the various platform solutions. In doing so, Unicode does provide a way around the historical platform-dependent solutions. Nonetheless, few if any Unicode solutions have adopted these Unicode line and paragraph separators as the sole canonical line ending characters. However, a common approach to solving this issue is through newline normalization. This is achieved with the Cocoa text system in Mac OS X and also with W3C XML and HTML recommendations. In this approach, every possible newline character is converted internally to a common newline (which one does not really matter since it is an internal operation just for rendering). In other words, the text system can correctly treat the character as a newline, regardless of the input's actual encoding.

Issues edit

Character unification edit

Han unification edit

Main article: Han unification

The Ideographic Research Group (IRG) is tasked with advising the Consortium and ISO regarding Han unification, or Unihan, especially the further addition of CJK unified and compatibility ideographs to the repertoire. The IRG is composed of experts from each region that has historically used Chinese characters. However, despite the deliberation within the committee, Han unification has consistently been one of the most contested aspects of The Unicode Standard since the genesis of the project.[93]

Existing character set standards such as the Japanese JIS X 0208 (encoded by Shift JIS) defined unification criteria, meaning rules for determining when a variant Chinese character is to be considered a handwriting/font difference (and thus unified), versus a spelling difference (to be encoded separately). Unicode's character model for CJK characters was based on the unification criteria used by JIS X 0208, as well as those developed by the Association for a Common Chinese Code in China.[94] Due to the standard's principle of encoding semantic instead of stylistic variants, Unicode has received criticism for not assigning code points to certain rare and archaic kanji variants, possibly complicating processing of ancient and uncommon Japanese names. Since it places particular emphasis on Chinese, Japanese and Korean sharing many characters in common, Han unification is also sometimes perceived as treating the three as the same thing.[95]

Less-frequently-used alternative encodings exist, often predating Unicode, with character models differing from this paradigm, aimed at preserving the various stylistic differences between regional and/or nonstandard character forms. One example is the TRON Code favored by some users for handling historical Japanese text, though not widely adopted among the Japanese public. Another is the CCCII encoding adopted by library systems in Hong Kong, Taiwan and the United States. These have their own drawbacks in general use, leading to the Big5 encoding (introduced in 1984, four years after CCCII) having become more common than CCCII outside of library systems.[96] Although work at Apple based on Research Libraries Group's CJK Thesaurus, which was used to maintain the EACC variant of CCCII, was one of the direct predecessors of Unicode's Unihan set, Unicode adopted the JIS-style unification model.[94]

The earliest version of Unicode had a repertoire of fewer than 21,000 Han characters, largely limited to those in relatively common modern usage. As of version 15.1, the standard now encodes more than 97,000 Han characters, and work is continuing to add thousands more—largely historical and dialectal variant characters used throughout the Sinosphere.

Modern typefaces provide a means to address some of the practical issues in depicting unified Han characters with various regional graphical representations. The 'locl' OpenType table allows a renderer to select a different glyph for each code point based on the text locale.[97] The Unicode variation sequences can also provide in-text annotations for a desired glyph selection; this requires registration of the specific variant in the Ideographic Variation Database.

Italic or cursive characters in Cyrillic edit

 
Various Cyrillic characters shown with upright, oblique, and italic alternate forms

If the appropriate glyphs for characters in the same script differ only in the italic, Unicode has generally unified them, as can be seen in the comparison among a set of seven characters' italic glyphs as typically appearing in Russian, traditional Bulgarian, Macedonian, and Serbian texts at right, meaning that the differences are displayed through smart font technology or manually changing fonts. The same OpenType 'locl' technique is used.[98]

Localised case pairs edit

For use in the Turkish alphabet and Azeri alphabet, Unicode includes a separate dotless lowercase I (ı) and a dotted uppercase I (İ). However, the usual ASCII letters are used for the lowercase dotted I and the uppercase dotless I, matching how they are handled in the earlier ISO 8859-9. As such, case-insensitive comparisons for those languages have to use different rules than case-insensitive comparisons for other languages using the Latin script.[99]

By contrast, the Icelandic eth (ð), the barred D (đ) and the retroflex D (ɖ), which usually[note 3] look the same in uppercase (Đ), are given the opposite treatment, and encoded separately in both letter-cases (in contrast to the earlier ISO 6937, which unifies the uppercase forms). Although it allows for case-insensitive comparison without needing to know the language of the text, this approach also has issues, requiring security measures relating to homoglyph attacks.[100]

Diacritics on lowercase I edit

 
Localised forms of the letter í (I with acute accent)

Whether the lowercase letter I is expected to retain its tittle when a diacritic applies also depends on local conventions.

Security edit

Unicode has a large number of homoglyphs, many of which look very similar or identical to ASCII letters. Substitution of these can make an identifier or URL that looks correct, but directs to a different location than expected.[101] Additionally, homoglyphs can also be used for manipulating the output of natural language processing (NLP) systems.[102] Mitigation requires disallowing these characters, displaying them differently, or requiring that they resolve to the same identifier;[103] all of this is complicated due to the huge and constantly changing set of characters.[104][105]

A security advisory was released in 2021 by two researchers, one from the University of Cambridge and the other from the University of Edinburgh, in which they assert that the BiDi marks can be used to make large sections of code do something different from what they appear to do. The problem was named "Trojan Source".[106] In response, code editors started highlighting marks to indicate forced text-direction changes.[107]

Mapping to legacy character sets edit

Unicode was designed to provide code-point-by-code-point round-trip format conversion to and from any preexisting character encodings, so that text files in older character sets can be converted to Unicode and then back and get back the same file, without employing context-dependent interpretation. That has meant that inconsistent legacy architectures, such as combining diacritics and precomposed characters, both exist in Unicode, giving more than one method of representing some text. This is most pronounced in the three different encoding forms for Korean Hangul. Since version 3.0, any precomposed characters that can be represented by a combined sequence of already existing characters can no longer be added to the standard to preserve interoperability between software using different versions of Unicode.

Injective mappings must be provided between characters in existing legacy character sets and characters in Unicode to facilitate conversion to Unicode and allow interoperability with legacy software. Lack of consistency in various mappings between earlier Japanese encodings such as Shift-JIS or EUC-JP and Unicode led to round-trip format conversion mismatches, particularly the mapping of the character JIS X 0208 '～' (1-33, WAVE DASH), heavily used in legacy database data, to either U+FF5E ～ FULLWIDTH TILDE (in Microsoft Windows) or U+301C 〜 WAVE DASH (other vendors).[108]

Some Japanese computer programmers objected to Unicode because it requires them to separate the use of U+005C \ REVERSE SOLIDUS (backslash) and U+00A5 ¥ YEN SIGN, which was mapped to 0x5C in JIS X 0201, and a lot of legacy code exists with this usage.[109] (This encoding also replaces tilde '~' 0x7E with macron '¯', now 0xAF.) The separation of these characters exists in ISO 8859-1, from long before Unicode.

Indic scripts edit

Further information: Tamil All Character Encoding

Indic scripts such as Tamil and Devanagari are each allocated only 128 code points, matching the ISCII standard. The correct rendering of Unicode Indic text requires transforming the stored logical order characters into visual order and the forming of ligatures (also known as conjuncts) out of components. Some local scholars argued in favor of assignments of Unicode code points to these ligatures, going against the practice for other writing systems, though Unicode contains some Arabic and other ligatures for backward compatibility purposes only.[110][111][112] Encoding of any new ligatures in Unicode will not happen, in part, because the set of ligatures is font-dependent, and Unicode is an encoding independent of font variations. The same kind of issue arose for the Tibetan script in 2003 when the Standardization Administration of China proposed encoding 956 precomposed Tibetan syllables,[113] but these were rejected for encoding by the relevant ISO committee (ISO/IEC JTC 1/SC 2).[114]

Thai alphabet support has been criticized for its ordering of Thai characters. The vowels เ, แ, โ, ใ, ไ that are written to the left of the preceding consonant are in visual order instead of phonetic order, unlike the Unicode representations of other Indic scripts. This complication is due to Unicode inheriting the Thai Industrial Standard 620, which worked in the same way, and was the way in which Thai had always been written on keyboards. This ordering problem complicates the Unicode collation process slightly, requiring table lookups to reorder Thai characters for collation.[95] Even if Unicode had adopted encoding according to spoken order, it would still be problematic to collate words in dictionary order. E.g., the word แสดง [sa dɛːŋ] "perform" starts with a consonant cluster "สด" (with an inherent vowel for the consonant "ส"), the vowel แ-, in spoken order would come after the ด, but in a dictionary, the word is collated as it is written, with the vowel following the ส.

Combining characters edit

Main article: Combining character
See also: Unicode normalization § Normalization

Characters with diacritical marks can generally be represented either as a single precomposed character or as a decomposed sequence of a base letter plus one or more non-spacing marks. For example, ḗ (precomposed e with macron and acute above) and ḗ (e followed by the combining macron above and combining acute above) should be rendered identically, both appearing as an e with a macron (◌̄) and acute accent (◌́), but in practice, their appearance may vary depending upon what rendering engine and fonts are being used to display the characters. Similarly, underdots, as needed in the romanization of Indic, will often be placed incorrectly.[citation needed] Unicode characters that map to precomposed glyphs can be used in many cases, thus avoiding the problem, but where no precomposed character has been encoded, the problem can often be solved by using a specialist Unicode font such as Charis SIL that uses Graphite, OpenType ('gsub'), or AAT technologies for advanced rendering features.

Anomalies edit

Main article: Unicode alias names and abbreviations

The Unicode Standard has imposed rules intended to guarantee stability.[115] Depending on the strictness of a rule, a change can be prohibited or allowed. For example, a "name" given to a code point cannot and will not change. But a "script" property is more flexible, by Unicode's own rules. In version 2.0, Unicode changed many code point "names" from version 1. At the same moment, Unicode stated that, thenceforth, an assigned name to a code point would never change. This implies that when mistakes are published, these mistakes cannot be corrected, even if they are trivial (as happened in one instance with the spelling BRAKCET for BRACKET in a character name). In 2006 a list of anomalies in character names was first published, and, as of June 2021, there were 104 characters with identified issues,[116] for example:

While Unicode defines the script designator (name) to be "Phags_Pa", in that script's character names, a hyphen is added: U+A840 ꡀ PHAGS-PA LETTER KA.[119][120] This, however, is not an anomaly, but the rule: hyphens are replaced by underscores in script designators.[119]

See also edit

Notes edit

  1. ^ Sometimes abbreviated as TUS.[1][2]
  2. ^ "A Unicode Standard Annex (UAX) forms an integral part of The Unicode Standard, but is published as a separate document."[1]
  3. ^ Rarely, the uppercase Icelandic eth may instead be written in an insular style (Ꝺ) with the crossbar positioned on the stem, particularly if it needs to be distinguished from the uppercase retroflex D (see African Reference Alphabet).

References edit

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    Unicode arose as the result of eight years of working experience with XCCS. Its fundamental differences from XCCS were proposed by Peter Fenwick and Dave Opstad (pure 16-bit codes) and by Lee Collins (ideographic character unification). Unicode retains the many features of XCCS whose utility has been proved over the years in an international line of communication multilingual system products.
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Further reading edit

  • Julie D. Allen. The Unicode Standard, Version 6.0, The Unicode Consortium, Mountain View, 2011, ISBN 9781936213016, (Unicode 6.0.0).
  • The Complete Manual of Typography, James Felici, Adobe Press; 1st edition, 2002. ISBN 0-321-12730-7
  • The Unicode Standard, Version 3.0, The Unicode Consortium, Addison-Wesley Longman, Inc., April 2000. ISBN 0-201-61633-5
  • The Unicode Standard, Version 4.0, The Unicode Consortium, Addison-Wesley Professional, 27 August 2003. ISBN 0-321-18578-1
  • The Unicode Standard, Version 5.0, Fifth Edition, The Unicode Consortium, Addison-Wesley Professional, 27 October 2006. ISBN 0-321-48091-0-->
  • Unicode Demystified: A Practical Programmer's Guide to the Encoding Standard, Richard Gillam, Addison-Wesley Professional; 1st edition, 2002. ISBN 0-201-70052-2
  • Unicode Explained, Jukka K. Korpela, O'Reilly; 1st edition, 2006. ISBN 0-596-10121-X
  • Unicode: A Primer, Tony Graham, M&T books, 2000. ISBN 0-7645-4625-2.
  • Haralambous, Yannis; Martin Dürst (2019). "Unicode from a Linguistic Point of View". In Haralambous, Yannis (ed.). Proceedings of Graphemics in the 21st Century, Brest 2018. Brest: Fluxus Editions. pp. 167–183. doi:10.36824/2018-graf-hara1. ISBN 978-2-9570549-1-6.

External links edit

  • Unicode, Inc.
    • Unicode Technical Site
      • The Unicode Standard
        • Unicode Character Code Charts
        • Unicode Character Name Index
  • Alan Wood's Unicode Resources – contains lists of word processors with Unicode capability; fonts and characters are grouped by type; characters are presented in lists, not grids.
  • Unicode at Curlie
  • Unicode BMP Fallback Font – displays the Unicode 6.1 value of any character in a document, including in the Private Use Area, rather than the glyph itself.
  • The World's Writing Systems, all 294 known writing systems with their Unicode status (131 not yet encoded as of 2023)

January 01, 1970
unicode, formally, standard, note, text, encoding, standard, maintained, consortium, designed, support, text, written, world, major, writing, systems, version, standard, defines, 149813, characters, scripts, used, various, ordinary, literary, academic, technic. Unicode formally The Unicode Standard note 1 is a text encoding standard maintained by the Unicode Consortium designed to support the use of text written in all of the world s major writing systems Version 15 1 of the standard A defines 149813 characters 3 and 161 scripts used in various ordinary literary academic and technical contexts UnicodeLogo of the Unicode ConsortiumAlias es Universal Coded Character Set UCS ISO IEC 10646Language s See list of scriptsStandardUnicode StandardEncoding formatsUTF 8UTF 16GB18030UTF 32BOCUSCSU uncommon UTF 7UTF 1 obsolete Preceded byISO IEC 8859various othersOfficial websiteTechnical websitevte This article contains uncommon Unicode characters Without proper rendering support you may see question marks boxes or other symbols Many common characters including numerals punctuation and other symbols are unified within the standard and are not treated as specific to any given writing system Unicode encodes thousands of emoji with the continued development thereof conducted by the Consortium as a part of the standard 4 Moreover the widespread adoption of Unicode was in large part responsible for the initial popularization of emoji outside of Japan Unicode is ultimately capable of encoding more than 1 1 million characters Unicode has largely supplanted the previous environment of myriad incompatible character sets each used within different locales and on different computer architectures Unicode is used to encode the vast majority of text on the Internet including most web pages and relevant Unicode support has become a common consideration in contemporary software development The Unicode character repertoire is synchronized with ISO IEC 10646 each being code for code identical with one another However The Unicode Standard is more than just a repertoire within which characters are assigned To aid developers and designers the standard also provides charts and reference data as well as annexes explaining concepts germane to various scripts providing guidance for their implementation Topics covered by these annexes include character normalization character composition and decomposition collation and directionality 5 Unicode text is processed and stored as binary data using one of several encodings which define how to translate the standard s abstracted codes for characters into sequences of bytes The Unicode Standard itself defines three encodings UTF 8 UTF 16 and UTF 32 though several others exist Of these UTF 8 is the most widely used by a large margin in part due to its backwards compatibility with ASCII Contents 1 Origin and development 1 1 History 1 2 Unicode Consortium 1 3 Scripts covered 1 4 Script Encoding Initiative 1 5 Versions 1 6 Projected versions 2 Architecture and terminology 2 1 Codespace and code points 2 2 Code planes and blocks 2 3 General Category property 2 4 Abstract characters 2 5 Ready made versus composite characters 2 6 Ligatures 2 7 Standardized subsets 2 8 Mapping and encodings 3 Adoption 3 1 Operating systems 3 2 Input methods 3 3 Email 3 4 Web 3 5 Fonts 3 6 Newlines 4 Issues 4 1 Character unification 4 1 1 Han unification 4 1 2 Italic or cursive characters in Cyrillic 4 1 3 Localised case pairs 4 1 4 Diacritics on lowercase I 4 2 Security 4 3 Mapping to legacy character sets 4 4 Indic scripts 4 5 Combining characters 4 6 Anomalies 5 See also 6 Notes 7 References 8 Further reading 9 External linksOrigin and development editUnicode was originally designed with the intent of transcending limitations present in all text encodings designed up to that point each encoding was relied upon for use in its own context but with no particular expectation of compatibility with any other Indeed any two encodings chosen were often totally unworkable when used together with text encoded in one interpreted as garbage characters by the other Most encodings had only been designed to facilitate interoperation between a handful of scripts often primarily between a given script and Latin characters not between a large number of scripts and not with all of the scripts supported being treated in a consistent manner The philosophy that underpins Unicode seeks to encode the underlying characters graphemes and grapheme like units rather than graphical distinctions considered mere variant glyphs thereof that are instead best handled by the typeface through the use of markup or by some other means In particularly complex cases such as the treatment of orthographical variants in Han characters there is considerable disagreement regarding which differences justify their own encodings and which are only graphical variants of other characters At the most abstract level Unicode assigns a unique number called a code point to each character Many issues of visual representation including size shape and style are intended to be up to the discretion of the software actually rendering the text such as a web browser or word processor However partially with the intent of encouraging rapid adoption the simplicity of this original model has become somewhat more elaborate over time and various pragmatic concessions have been made over the course of the standard s development The first 256 code points mirror the ISO IEC 8859 1 standard with the intent of trivializing the conversion of text already written in Western European scripts To preserve the distinctions made by different legacy encodings therefore allowing for conversion between them and Unicode without any loss of information many characters nearly identical to others in both appearance and intended function were given distinct code points For example the Halfwidth and Fullwidth Forms block encompasses a full semantic duplicate of the Latin alphabet because legacy CJK encodings contained both fullwidth matching the width of CJK characters and halfwidth matching ordinary Latin script characters The Unicode Bulldog Award is given to people deemed to be influential in Unicode s development with recipients including Tatsuo Kobayashi Thomas Milo Roozbeh Pournader Ken Lunde and Michael Everson 6 History edit The origins of Unicode can be traced back to the 1980s to a group of individuals with connections to Xerox s Character Code Standard XCCS 7 In 1987 Xerox employee Joe Becker along with Apple employees Lee Collins and Mark Davis started investigating the practicalities of creating a universal character set 8 With additional input from Peter Fenwick and Dave Opstad 7 Becker published a draft proposal for an international multilingual text character encoding system in August 1988 tentatively called Unicode He explained that the name Unicode is intended to suggest a unique unified universal encoding 7 In this document entitled Unicode 88 Becker outlined a scheme using 16 bit characters 7 Unicode is intended to address the need for a workable reliable world text encoding Unicode could be roughly described as wide body ASCII that has been stretched to 16 bits to encompass the characters of all the world s living languages In a properly engineered design 16 bits per character are more than sufficient for this purpose This design decision was made based on the assumption that only scripts and characters in modern use would require encoding 7 Unicode gives higher priority to ensuring utility for the future than to preserving past antiquities Unicode aims in the first instance at the characters published in the modern text e g in the union of all newspapers and magazines printed in the world in 1988 whose number is undoubtedly far below 214 16 384 Beyond those modern use characters all others may be defined to be obsolete or rare these are better candidates for private use registration than for congesting the public list of generally useful Unicode In early 1989 the Unicode working group expanded to include Ken Whistler and Mike Kernaghan of Metaphor Karen Smith Yoshimura and Joan Aliprand of Research Libraries Group and Glenn Wright of Sun Microsystems In 1990 Michel Suignard and Asmus Freytag of Microsoft and NeXT s Rick McGowan had also joined the group By the end of 1990 most of the work of remapping existing standards had been completed and a final review draft of Unicode was ready The Unicode Consortium was incorporated in California on 3 January 1991 9 and the first volume of The Unicode Standard was published that October The second volume now adding Han ideographs was published in June 1992 In 1996 a surrogate character mechanism was implemented in Unicode 2 0 so that Unicode was no longer restricted to 16 bits This increased the Unicode codespace to over a million code points which allowed for the encoding of many historic scripts such as Egyptian hieroglyphs and thousands of rarely used or obsolete characters that had not been anticipated for inclusion in the standard Among these characters are various rarely used CJK characters many mainly being used in proper names making them far more necessary for a universal encoding than the original Unicode architecture envisioned 10 Version 1 0 of Microsoft s TrueType specification published in 1992 used the name Apple Unicode instead of Unicode for the Platform ID in the naming table Unicode Consortium edit Main article Unicode Consortium The Unicode Consortium is a nonprofit organization that coordinates Unicode s development Full members include most of the main computer software and hardware companies and few others with any interest in text processing standards including Adobe Apple Google IBM Meta previously as Facebook Microsoft Netflix and SAP 11 Over the years several countries or government agencies have been members of the Unicode Consortium Presently only the Ministry of Endowments and Religious Affairs Oman is a full member with voting rights 11 The Consortium has the ambitious goal of eventually replacing existing character encoding schemes with Unicode and its standard Unicode Transformation Format UTF schemes as many of the existing schemes are limited in size and scope and are incompatible with multilingual environments Scripts covered edit Main article Script Unicode nbsp Many modern applications can render a substantial subset of the many scripts in Unicode as demonstrated by this screenshot from the OpenOffice org application Unicode currently covers most major writing systems in use today 12 better source needed As of 2024 update a total of 161 scripts 13 are included in the latest version of Unicode covering alphabets abugidas and syllabaries although there are still scripts that are not yet encoded particularly those mainly used in historical liturgical and academic contexts Further additions of characters to the already encoded scripts as well as symbols in particular for mathematics and music in the form of notes and rhythmic symbols also occur The Unicode Roadmap Committee Michael Everson Rick McGowan Ken Whistler V S Umamaheswaran 14 maintain the list of scripts that are candidates or potential candidates for encoding and their tentative code block assignments on the Unicode Roadmap 15 page of the Unicode Consortium website For some scripts on the Roadmap such as Jurchen and Khitan large script encoding proposals have been made and they are working their way through the approval process For other scripts such as Numidian and Rongorongo no proposal has yet been made and they await agreement on character repertoire and other details from the user communities involved Some modern invented scripts which have not yet been included in Unicode e g Tengwar or which do not qualify for inclusion in Unicode due to lack of real world use e g Klingon are listed in the ConScript Unicode Registry along with unofficial but widely used Private Use Areas code assignments There is also a Medieval Unicode Font Initiative focused on special Latin medieval characters Part of these proposals has been already included in Unicode Script Encoding Initiative edit The Script Encoding Initiative 16 a project run by Deborah Anderson at the University of California Berkeley was founded in 2002 with the goal of funding proposals for scripts not yet encoded in the standard The project has become a major source of proposed additions to the standard in recent years 17 Versions edit The Unicode Consortium together with the ISO have developed a shared repertoire following the initial publication of The Unicode Standard Unicode and the ISO s Universal Coded Character Set UCS use identical character names and code points However the Unicode versions do differ from their ISO equivalents in two significant ways While the UCS is a simple character map Unicode specifies the rules algorithms and properties necessary to achieve interoperability between different platforms and languages Thus The Unicode Standard includes more information covering in depth topics such as bitwise encoding collation and rendering It also provides a comprehensive catalog of character properties including those needed for supporting bidirectional text as well as visual charts and reference data sets to aid implementers Previously The Unicode Standard was sold as a print volume containing the complete core specification standard annexes note 2 and code charts However version 5 0 published in 2006 was the last version printed this way Starting with version 5 2 only the core specification published as a print on demand paperback may be purchased 18 The full text on the other hand is published as a free PDF on the Unicode website A practical reason for this publication method highlights the second significant difference between the UCS and Unicode the frequency with which updated versions are released and new characters added The Unicode Standard has regularly released annual expanded versions occasionally with more than one version released in a calendar year and with rare cases where the scheduled release had to be postponed For instance in April 2020 a month after version 13 0 was published the Unicode Consortium announced they had changed the intended release date for version 14 0 pushing it back six months to September 2021 due to the COVID 19 pandemic Unicode 15 1 the latest version was released on 12 September 2023 It is a minor version update to version 15 0 released on 13 September 2022 which added a total of 4 489 new characters including two new scripts an extension to the CJK Unified Ideographs block and multiple additions to existing blocks 33 new emoji were added such as the wireless network symbol and additional colored hearts 19 20 Thus far the following versions of The Unicode Standard have been published Update versions which do not include any changes to character repertoire are signified by the third number e g version 4 0 1 and are omitted in the table below 21 Unicode version history and notable changes to characters and scripts Version Date Book UCS edition Total Details Scripts Characters a 1 0 0 22 October 1991 ISBN 0 201 56788 1 vol 1 24 7129 Initial scripts covered Arabic Armenian Bengali Bopomofo Cyrillic Devanagari Georgian Greek and Coptic Gujarati Gurmukhi Hangul Hebrew Hiragana Kannada Katakana Lao Latin Malayalam Odia Tamil Telugu Thai and Tibetan 1 0 1 23 June 1992 ISBN 0 201 60845 6 vol 2 25 28327 21204 6 The initial 20 902 CJK Unified Ideographs 1 1 24 June 1993 ISO IEC 10646 1 1993 b 24 34168 5963 9 33 reclassified as control characters 4 306 Hangul syllables Tibetan removed 2 0 25 July 1996 ISBN 0 201 48345 9 25 38885 11373 6656 Original set of Hangul syllables removed new set of 11 172 Hangul syllables added at new location Tibetan added back in a new location and with a different character repertoire Surrogate character mechanism defined Plane 15 and Plane 16 Private Use Areas allocated 2 1 26 May 1998 38887 2 U 20AC EURO SIGN U FFFC OBJECT REPLACEMENT CHARACTER 26 3 0 27 September 1999 ISBN 0 201 61633 5 ISO IEC 10646 1 2000 38 49194 10307 Cherokee Geʽez Khmer Mongolian Burmese Ogham runes Sinhala Syriac Thaana Canadian Aboriginal syllabics and Yi Syllables Braille patterns 3 1 28 March 2001 ISO IEC 10646 1 2000 c ISO IEC 10646 2 2001 41 94140 44946 Deseret Gothic and Old Italic sets of symbols for Western and Byzantine music 42 711 additional CJK Unified Ideographs 3 2 29 March 2002 45 95156 1016 Philippine scripts Buhid Hanunoo Tagalog and Tagbanwa 4 0 30 April 2003 ISBN 0 321 18578 1 ISO IEC 10646 2003 d 52 96382 1226 Cypriot syllabary Limbu Linear B Osmanya Shavian Tai Le and Ugaritic Hexagram symbols 4 1 31 March 2005 59 97655 1273 Buginese Glagolitic Kharosthi New Tai Lue Old Persian Sylheti Nagri and Tifinagh Coptic disunified from Greek ancient Greek numbers and musical symbols First named character sequences were introduced 32 5 0 July 2006 ISBN 0 321 48091 0 64 99024 1369 Balinese cuneiform N Ko ʼPhags pa Phoenician 33 5 1 34 April 2008 75 100648 1624 Carian Cham Kayah Li Lepcha Lycian Lydian Ol Chiki Rejang Saurashtra Sundanese and Vai sets of symbols for the Phaistos Disc Mahjong tiles Domino tiles additions to Burmese Scribal abbreviations U 1E9E ẞ LATIN CAPITAL LETTER SHARP S 5 2 35 October 2009 ISBN 978 1 936213 00 9 90 107296 6648 Avestan Bamum Gardiner s sign list of Egyptian hieroglyphs Imperial Aramaic Inscriptional Pahlavi Inscriptional Parthian Javanese Kaithi Lisu Meetei Mayek Old South Arabian Old Turkic Samaritan Tai Tham and Tai Viet additional CJK Unified Ideographs Jamo for Old Hangul Vedic Sanskrit 6 0 36 October 2010 ISBN 978 1 936213 01 6 ISO IEC 10646 2010 e 93 109384 2088 Batak Brahmi Mandaic playing card symbols transport and map symbols alchemical symbols emoticons and emoji 37 additional CJK Unified Ideographs 6 1 38 January 2012 ISBN 978 1 936213 02 3 ISO IEC 10646 2012 f 100 110116 732 Chakma Meroitic cursive Meroitic hieroglyphs Miao Sharada Sora Sompeng and Takri 6 2 39 September 2012 ISBN 978 1 936213 07 8 110117 1 U 20BA TURKISH LIRA SIGN 6 3 40 September 2013 ISBN 978 1 936213 08 5 110122 5 5 bidirectional formatting characters 7 0 41 June 2014 ISBN 978 1 936213 09 2 123 112956 2834 Bassa Vah Caucasian Albanian Duployan Elbasan Grantha Khojki Khudawadi Linear A Mahajani Manichaean Mende Kikakui Modi Mro Nabataean Old North Arabian Old Permic Pahawh Hmong Palmyrene Pau Cin Hau Psalter Pahlavi Siddham Tirhuta Warang Citi and dingbats 8 0 42 June 2015 ISBN 978 1 936213 10 8 ISO IEC 10646 2014 g 129 120672 7716 Ahom Anatolian hieroglyphs Hatran Multani Old Hungarian SignWriting additional CJK Unified Ideographs lowercase letters for Cherokee 5 emoji skin tone modifiers 9 0 45 June 2016 ISBN 978 1 936213 13 9 135 128172 7500 Adlam Bhaiksuki Marchen Newa Osage Tangut 72 emoji 46 10 0 47 June 2017 ISBN 978 1 936213 16 0 ISO IEC 10646 2017 h 139 136690 8518 Zanabazar Square Soyombo Masaram Gondi Nushu hentaigana 7 494 CJK Unified Ideographs 56 emoji bitcoin symbol 11 0 48 June 2018 ISBN 978 1 936213 19 1 146 137374 684 Dogra Georgian Mtavruli capital letters Gunjala Gondi Hanifi Rohingya Indic Siyaq Numbers Makasar Medefaidrin Old Sogdian and Sogdian Maya numerals 5 CJK Unified Ideographs symbols for xiangqi and star ratings 145 emoji 12 0 49 March 2019 ISBN 978 1 936213 22 1 150 137928 554 Elymaic Nandinagari Nyiakeng Puachue Hmong Wancho Miao script hiragana and katakana small letters Tamil historic fractions and symbols Lao letters for Pali Latin letters for Egyptological and Ugaritic transliteration hieroglyph format controls 61 emoji 12 1 50 May 2019 ISBN 978 1 936213 25 2 137929 1 U 32FF SQUARE ERA NAME REIWA 13 0 51 March 2020 ISBN 978 1 936213 26 9 ISO IEC 10646 2020 52 154 143859 5930 Chorasmian Dhives Akuru Khitan small script Yezidi 4 969 CJK ideographs Arabic script additions used to write Hausa Wolof and other African languages additions used to write Hindko and Punjabi in Pakistan Bopomofo additions used for Cantonese Creative Commons license symbols graphic characters for compatibility with teletext and home computer systems 55 emoji 14 0 53 September 2021 ISBN 978 1 936213 29 0 159 144697 838 Toto Cypro Minoan Vithkuqi Old Uyghur Tangsa extended IPA Arabic script additions for use in languages across Africa and in Iran Pakistan Malaysia Indonesia Java and Bosnia additions for honorifics and Quranic use additions to support languages in North America the Philippines India and Mongolia U 20C0 SOM SIGN Znamenny musical notation 37 emoji 15 0 54 September 2022 ISBN 978 1 936213 32 0 161 149186 4489 Kawi and Mundari 20 emoji 4 192 CJK ideographs control characters for Egyptian hieroglyphs 15 1 55 September 2023 ISBN 978 1 936213 33 7 149813 627 Additional CJK ideographs The total number of graphic and format characters excluding private use characters control characters noncharacters and surrogate code points 2 0 added Amendments 5 6 and 72 1 added two characters from Amendment 18 3 2 added Amendment 1 4 1 added Amendment 15 0 added Amendment 2 as well as four characters from Amendment 35 1 added Amendment 45 2 added Amendments 5 and 6 Plus the Indian rupee sign 6 2 added the Turkish lira sign6 3 added five additional characters7 0 added Amendments 1 and 2 as well as the ruble sign Plus Amendment 1 as well as the Lari sign nine CJK unified ideographs and 41 emoji 43 9 0 added Amendment 2 as well as Adlam Newa Japanese TV symbols and 74 emoji and symbols 44 Plus 56 emoji 285 hentaigana characters and 3 Zanabazar Square characters11 0 added 46 Mtavruli Georgian capital letters 5 CJK unified ideographs and 66 emoji12 0 added 62 additional characters Projected versions edit The Unicode Consortium normally releases a new version of The Unicode Standard once a year or occasionally twice a year Version 16 0 the next major version is scheduled to be published in 2024 and is projected to include six new scripts Todhri Sunuwar Gurung Khema Kirat Rai Garay and Ol Onal additional Burmese numerals for Shan and Mon alphabets additional symbols for legacy computing and at least six new emoji 56 57 Architecture and terminology editSee also Universal Character Set characters Codespace and code points edit The Unicode Standard defines a codespace 58 a sequence of integers called code points 59 in the range from 0 to 1114 111 notated according to the standard as U 0000 U 10FFFF 60 The codespace is a systematic architecture independent representation of The Unicode Standard actual text is processed as binary data via one of several Unicode encodings such as UTF 8 In this normative notation the two character prefix U always precedes a written code point 61 and the code points themselves are written as hexadecimal numbers At least four hexadecimal digits are always written with leading zeros prepended as needed For example the code point U 00F7 DIVISION SIGN is padded with two leading zeros but U 13254 𓉔 EGYPTIAN HIEROGLYPH O004 nbsp is not padded 62 There are a total of 220 216 211 1112 064 valid code points within the codespace This number arises from the limitations of the UTF 16 character encoding which can encode the 216 code points in the range U 0000 through U FFFF except for the 211 code points in the range U D800 through U DFFF which are used as surrogate pairs to encode the 220 code points in the range U 10000 through U 10FFFF Code planes and blocks edit Main article Plane Unicode The Unicode codespace is divided into 17 planes numbered 0 to 16 Plane 0 is the Basic Multilingual Plane BMP and contains the most commonly used characters All code points in the BMP are accessed as a single code unit in UTF 16 encoding and can be encoded in one two or three bytes in UTF 8 Code points in planes 1 through 16 the supplementary planes are accessed as surrogate pairs in UTF 16 and encoded in four bytes in UTF 8 Within each plane characters are allocated within named blocks of related characters The size of a block is always a multiple of 16 and is often a multiple of 128 but is otherwise arbitrary Characters required for a given script may be spread out over several different potentially disjunct blocks within the codespace General Category property edit Each code point is assigned a classification listed as the code point s General Category property Here at the uppermost level code points are categorized as one of Letter Mark Number Punctuation Symbol Separator or Other Under each category each code point is then further subcategorized In most cases other properties must be used to adequately describe all the characteristics of any given code point General Category Unicode Character Property a vte Value Category Major minor Basic type b Character assigned b Count c as of 15 1 Remarks L Letter LC Cased Letter Lu Ll and Lt only d Lu Letter uppercase Graphic Character 1 831 Ll Letter lowercase Graphic Character 2 233 Lt Letter titlecase Graphic Character 31 Ligatures or digraphs containing an uppercase followed by a lowercase part e g Dž Lj Nj and Dz Lm Letter modifier Graphic Character 397 A modifier letter Lo Letter other Graphic Character 132 234 An ideograph or a letter in a unicase alphabet M Mark Mn Mark nonspacing Graphic Character 1 985 Mc Mark spacing combining Graphic Character 452 Me Mark enclosing Graphic Character 13 N Number Nd Number decimal digit Graphic Character 680 All these and only these have Numeric Type De e Nl Number letter Graphic Character 236 Numerals composed of letters or letterlike symbols e g Roman numerals No Number other Graphic Character 915 E g vulgar fractions superscript and subscript digits P Punctuation Pc Punctuation connector Graphic Character 10 Includes spacing underscore characters such as and other spacing tie characters Unlike other punctuation characters these may be classified as word characters by regular expression libraries f Pd Punctuation dash Graphic Character 26 Includes several hyphen characters Ps Punctuation open Graphic Character 79 Opening bracket characters Pe Punctuation close Graphic Character 77 Closing bracket characters Pi Punctuation initial quote Graphic Character 12 Opening quotation mark Does not include the ASCII neutral quotation mark May behave like Ps or Pe depending on usage Pf Punctuation final quote Graphic Character 10 Closing quotation mark May behave like Ps or Pe depending on usage Po Punctuation other Graphic Character 628 S Symbol Sm Symbol math Graphic Character 948 Mathematical symbols e g Does not include parentheses and brackets which are in categories Ps and Pe Also does not include or which despite frequent use as mathematical operators are primarily considered to be punctuation Sc Symbol currency Graphic Character 63 Currency symbols Sk Symbol modifier Graphic Character 125 So Symbol other Graphic Character 6 639 Z Separator Zs Separator space Graphic Character 17 Includes the space but not TAB CR or LF which are Cc Zl Separator line Format Character 1 Only U 2028 LINE SEPARATOR LSEP Zp Separator paragraph Format Character 1 Only U 2029 PARAGRAPH SEPARATOR PSEP C Other Cc Other control Control Character 65 will never change e No name g lt control gt Cf Other format Format Character 170 Includes the soft hyphen joining control characters ZWNJ and ZWJ control characters to support bidirectional text and language tag characters Cs Other surrogate Surrogate Not only used in UTF 16 2 048 will never change e No name g lt surrogate gt Co Other private use Private use Character but no interpretation specified 137 468 total will never change e 6 400 in BMP 131 068 in Planes 15 16 No name g lt private use gt Cn Other not assigned Noncharacter Not 66 will not change unless the range of Unicode code points is expanded e No name g lt noncharacter gt Reserved Not 824 652 No name g lt reserved gt Table 4 4 General Category PDF The Unicode Standard Unicode Consortium September 2022 a b Table 2 3 Types of code points PDF The Unicode Standard Unicode Consortium September 2022 DerivedGeneralCategory txt The Unicode Consortium 2022 04 26 5 7 1 General Category Values UTR 44 Unicode Character Database Unicode Consortium 2020 03 04 a b c d e Unicode Character Encoding Stability Policies Property Value Stability Stability policy Some gc groups will never change gc Nd corresponds with Numeric Type De decimal Annex C Compatibility Properties word Unicode Regular Expressions Version 23 Unicode Consortium 2022 02 08 Unicode Technical Standard 18 a b c d e Table 4 9 Construction of Code Point Labels PDF The Unicode Standard Unicode Consortium September 2022 A Code Point Label may be used to identify a nameless code point E g lt control hhhh gt lt control 0088 gt The Name remains blank which can prevent inadvertently replacing in documentation a Control Name with a true Control code Unicode also uses lt not a character gt for lt noncharacter gt The 1024 points in the range U D800 U DBFF are known as high surrogate code points and code points in the range U DC00 U DFFF 1024 code points are known as low surrogate code points A high surrogate code point followed by a low surrogate code point forms a surrogate pair in UTF 16 in order to represent code points greater than U FFFF In principle these code points cannot otherwise be used though in practice this rule is often ignored especially when not using UTF 16 A small set of code points are guaranteed never to be assigned to characters although third parties may make independent use of them at their discretion There are 66 of these noncharacters U FDD0 U FDEF and the last two code points in each of the 17 planes e g U FFFE U FFFF U 1FFFE U 1FFFF U 10FFFE U 10FFFF The set of noncharacters is stable and no new noncharacters will ever be defined 63 Like surrogates the rule that these cannot be used is often ignored although the operation of the byte order mark assumes that U FFFE will never be the first code point in a text The exclusion of surrogates and noncharacters leaves 1111 998 code points available for use Private use code points are considered to be assigned but they intentionally have no interpretation specified by The Unicode Standard 64 such that any interchange of such code points requires an independent agreement between the sender and receiver as to their interpretation There are three private use areas in the Unicode codespace Private Use Area U E000 U F8FF 6400 characters Supplementary Private Use Area A U F0000 U FFFFD 65534 characters Supplementary Private Use Area B U 100000 U 10FFFD 65534 characters Graphic characters are those defined by The Unicode Standard to have particular semantics either having a visible glyph shape or representing a visible space As of Unicode 15 1 there are 149641 graphic characters Format characters are characters that do not have a visible appearance but may have an effect on the appearance or behavior of neighboring characters For example U 200C ZERO WIDTH NON JOINER and U 200D ZERO WIDTH JOINER may be used to change the default shaping behavior of adjacent characters e g to inhibit ligatures or request ligature formation There are 172 format characters in Unicode 15 1 65 code points the ranges U 0000 U 001F and U 007F U 009F are reserved as control codes corresponding to the C0 and C1 control codes as defined in ISO IEC 6429 U 0089 LINE TABULATION U 008A LINE FEED and U 000D CARRIAGE RETURN are widely used in texts using Unicode In a phenomenon known as mojibake the C1 code points are improperly decoded according to the Windows 1252 codepage previously widely used in Western European contexts Together graphic format control code and private use characters are collectively referred to as assigned characters Reserved code points are those code points that are valid and available for use but have not yet been assigned As of Unicode 15 1 there are 824652 reserved code points Abstract characters edit Further information Universal Character Set characters Characters grapheme clusters and glyphs The set of graphic and format characters defined by Unicode does not correspond directly to the repertoire of abstract characters representable under Unicode Unicode encodes characters by associating an abstract character with a particular code point 65 However not all abstract characters are encoded as a single Unicode character and some abstract characters may be represented in Unicode by a sequence of two or more characters For example a Latin small letter i with an ogonek a dot above and an acute accent which is required in Lithuanian is represented by the character sequence U 012F U 0307 U 0301 Unicode maintains a list of uniquely named character sequences for abstract characters that are not directly encoded in Unicode 66 All assigned characters have a unique and immutable name by which they are identified This immutability has been guaranteed since version 2 0 of The Unicode Standard by its Name Stability policy 63 In cases where a name is seriously defective and misleading or has a serious typographical error a formal alias may be defined that applications are encouraged to use in place of the official character name For example U A015 ꀕ YI SYLLABLE WU has the formal alias YI SYLLABLE ITERATION MARK and U FE18 PRESENTATION FORM FOR VERTICAL RIGHT WHITE LENTICULAR BRAKCET sic has the formal alias PRESENTATION FORM FOR VERTICAL RIGHT WHITE LENTICULAR BRACKET 67 Ready made versus composite characters edit Unicode includes a mechanism for modifying characters that greatly extends the supported repertoire of glyphs This covers the use of combining diacritical marks that may be added after the base character by the user Multiple combining diacritics may be simultaneously applied to the same character Unicode also contains precomposed versions of most letter diacritic combinations in normal use These make the conversion to and from legacy encodings simpler and allow applications to use Unicode as an internal text format without having to implement combining characters For example e can be represented in Unicode as U 0065 e LATIN SMALL LETTER E followed by U 0301 COMBINING ACUTE ACCENT and equivalently as the precomposed character U 00E9 e LATIN SMALL LETTER E WITH ACUTE Thus users often have multiple equivalent ways of encoding the same character The mechanism of canonical equivalence within The Unicode Standard ensures the practical interchangeability of these equivalent encodings An example of this arises with the Korean alphabet Hangul Unicode provides a mechanism for composing Hangul syllables from their individual Hangul Jamo subcomponents However it also provides 11172 combinations of precomposed syllables made from the most common jamo CJK characters presently only have codes for uncomposable radicals and precomposed forms Most Han characters have either been intentionally composed from or reconstructed as compositions of simpler orthographic elements called radicals so in principle Unicode could have enabled their composition as it did with Hangul While this could have greatly reduced the number of required code points as well as allowing the algorithmic synthesis of many arbitrary new characters the complexities of character etymologies and the post hoc nature of radical systems add immense complexity to the proposal Indeed attempts to design CJK encodings on the basis of composing radicals have been met with difficulties resulting from the reality that Chinese characters do not decompose as simply or as regularly as Hangul does The CJK Radicals Supplement block is assigned to the range U 2E80 U 2EFF and the Kangxi radicals are assigned to U 2F00 U 2FDF The Ideographic Description Sequences block covers the range U 2FF0 U 2FFB but The Unicode Standard warns against using its characters as an alternate representation for characters encoded elsewhere This process is different from a formal encoding of an ideograph There is no canonical description of unencoded ideographs there is no semantic assigned to described ideographs there is no equivalence defined for described ideographs Conceptually ideographic descriptions are more akin to the English phrase an e with an acute accent on it than to the character sequence lt U 0065 U 0301 gt Ligatures edit nbsp The Devanagari ddhrya ligature द ध र य द ध र य of JanaSanskritSans 68 nbsp The Arabic lam alif ligature ل ا لا Many scripts including Arabic and Devanagari have special orthographic rules that require certain combinations of letterforms to be combined into special ligature forms The rules governing ligature formation can be quite complex requiring special script shaping technologies such as ACE Arabic Calligraphic Engine by DecoType in the 1980s and used to generate all the Arabic examples in the printed editions of The Unicode Standard which became the proof of concept for OpenType by Adobe and Microsoft Graphite by SIL International or AAT by Apple Instructions are also embedded in fonts to tell the operating system how to properly output different character sequences A simple solution to the placement of combining marks or diacritics is assigning the marks a width of zero and placing the glyph itself to the left or right of the left sidebearing depending on the direction of the script they are intended to be used with A mark handled this way will appear over whatever character precedes it but will not adjust its position relative to the width or height of the base glyph it may be visually awkward and it may overlap some glyphs Real stacking is impossible but can be approximated in limited cases for example Thai top combining vowels and tone marks can just be at different heights to start with Generally this approach is only effective in monospaced fonts but may be used as a fallback rendering method when more complex methods fail Standardized subsets edit Several subsets of Unicode are standardized Microsoft Windows since Windows NT 4 0 supports WGL 4 with 657 characters which is considered to support all contemporary European languages using the Latin Greek or Cyrillic script Other standardized subsets of Unicode include the Multilingual European Subsets 69 MES 1 Latin scripts only 335 characters MES 2 Latin Greek and Cyrillic 1062 characters 70 and MES 3A amp MES 3B two larger subsets not shown here MES 2 includes every character in MES 1 and WGL 4 The standard DIN 91379 71 specifies a subset of Unicode letters special characters and sequences of letters and diacritic signs to allow the correct representation of names and to simplify data exchange in Europe This standard supports all of the official languages of all European Union countries as well as the German minority languages and the official languages of Iceland Liechtenstein Norway and Switzerland To allow the transliteration of names in other writing systems to the Latin script according to the relevant ISO standards all necessary combinations of base letters and diacritic signs are provided WGL 4 MES 1 and MES 2 Row Cells Range s 00 20 7E Basic Latin 00 7F A0 FF Latin 1 Supplement 80 FF 01 00 13 14 15 16 2B 2C 2D 2E 4D 4E 4F 50 7E 7F Latin Extended A 00 7F 8F 92 B7 DE EF FA FF Latin Extended B 80 FF 02 18 1B 1E 1F Latin Extended B 00 4F 59 7C 92 IPA Extensions 50 AF BB BD C6 C7 C9 D6 D8 DB DC DD DF EE Spacing Modifier Letters B0 FF 03 74 75 7A 7E 84 8A 8C 8E A1 A3 CE D7 DA E1 Greek 70 FF 04 00 5F 90 91 92 C4 C7 C8 CB CC D0 EB EE F5 F8 F9 Cyrillic 00 FF 1E 02 03 0A 0B 1E 1F 40 41 56 57 60 61 6A 6B 80 85 9B F2 F3 Latin Extended Additional 00 FF 1F 00 15 18 1D 20 45 48 4D 50 57 59 5B 5D 5F 7D 80 B4 B6 C4 C6 D3 D6 DB DD EF F2 F4 F6 FE Greek Extended 00 FF 20 13 14 15 17 18 19 1A 1B 1C 1D 1E 20 22 26 30 32 33 39 3A 3C 3E 44 4A General Punctuation 00 6F 7F 82 Superscripts and Subscripts 70 9F A3 A4 A7 AC AF Currency Symbols A0 CF 21 05 13 16 22 26 2E Letterlike Symbols 00 4F 5B 5E Number Forms 50 8F 90 93 94 95 A8 Arrows 90 FF 22 00 02 03 06 08 09 0F 11 12 15 19 1A 1E 1F 27 28 29 2A 2B 48 59 60 61 64 65 82 83 95 97 Mathematical Operators 00 FF 23 02 0A 20 21 29 2A Miscellaneous Technical 00 FF 25 00 02 0C 10 14 18 1C 24 2C 34 3C 50 6C Box Drawing 00 7F 80 84 88 8C 90 93 Block Elements 80 9F A0 A1 AA AC B2 BA BC C4 CA CB CF D8 D9 E6 Geometric Shapes A0 FF 26 3A 3C 40 42 60 63 65 66 6A 6B Miscellaneous Symbols 00 FF F0 01 02 Private Use Area 00 FF FB 01 02 Alphabetic Presentation Forms 00 4F FF FD Specials Rendering software that cannot process a Unicode character appropriately often displays it as an open rectangle or as U FFFD to indicate the position of the unrecognized character Some systems have made attempts to provide more information about such characters Apple s Last Resort font will display a substitute glyph indicating the Unicode range of the character and the SIL International s Unicode fallback font will display a box showing the hexadecimal scalar value of the character Mapping and encodings edit Several mechanisms have been specified for storing a series of code points as a series of bytes Unicode defines two mapping methods the Unicode Transformation Format UTF encodings and the Universal Coded Character Set UCS encodings An encoding maps possibly a subset of the range of Unicode code points to sequences of values in some fixed size range termed code units All UTF encodings map code points to a unique sequence of bytes 72 The numbers in the names of the encodings indicate the number of bits per code unit for UTF encodings or the number of bytes per code unit for UCS encodings and UTF 1 UTF 8 and UTF 16 are the most commonly used encodings UCS 2 is an obsolete subset of UTF 16 UCS 4 and UTF 32 are functionally equivalent UTF encodings include UTF 8 which uses one to four bytes per code point and has maximal compatibility with ASCII UTF 16 which uses either one or two 16 bit units per code point but cannot encode surrogates UTF 32 which uses one 32 bit unit per code point UTF EBCDIC not specified as part of The Unicode Standard which uses one to five bytes per code point intended to maximize compatibility with EBCDIC UTF 8 uses one to four bytes per code point and being compact for Latin scripts and ASCII compatible provides the de facto standard encoding for the interchange of Unicode text It is used by FreeBSD and most recent Linux distributions as a direct replacement for legacy encodings in general text handling The UCS 2 and UTF 16 encodings specify the Unicode byte order mark BOM for use at the beginnings of text files which may be used for byte order detection or byte endianness detection The BOM encoded as U FEFF ZERO WIDTH NO BREAK SPACE has the important property of unambiguity on byte reorder regardless of the Unicode encoding used U FFFE the result of byte swapping U FEFF does not equate to a legal character and U FEFF in places other than the beginning of text conveys the zero width non break space The same character converted to UTF 8 becomes the byte sequence EF BB BF The Unicode Standard allows the BOM can serve as a signature for UTF 8 encoded text where the character set is unmarked 73 Some software developers have adopted it for other encodings including UTF 8 in an attempt to distinguish UTF 8 from local 8 bit code pages However RFC 3629 the UTF 8 standard recommends that byte order marks be forbidden in protocols using UTF 8 but discusses the cases where this may not be possible In addition the large restriction on possible patterns in UTF 8 for instance there cannot be any lone bytes with the high bit set means that it should be possible to distinguish UTF 8 from other character encodings without relying on the BOM In UTF 32 and UCS 4 one 32 bit code unit serves as a fairly direct representation of any character s code point although the endianness which varies across different platforms affects how the code unit manifests as a byte sequence In the other encodings each code point may be represented by a variable number of code units UTF 32 is widely used as an internal representation of text in programs as opposed to stored or transmitted text since every Unix operating system that uses the gcc compilers to generate software uses it as the standard wide character encoding Some programming languages such as Seed7 use UTF 32 as an internal representation for strings and characters Recent versions of the Python programming language beginning with 2 2 may also be configured to use UTF 32 as the representation for Unicode strings effectively disseminating such encoding in high level coded software Punycode another encoding form enables the encoding of Unicode strings into the limited character set supported by the ASCII based Domain Name System DNS The encoding is used as part of IDNA which is a system enabling the use of Internationalized Domain Names in all scripts that are supported by Unicode Earlier and now historical proposals include UTF 5 and UTF 6 GB18030 is another encoding form for Unicode from the Standardization Administration of China It is the official character set of the People s Republic of China PRC BOCU 1 and SCSU are Unicode compression schemes The April Fools Day RFC of 2005 specified two parody UTF encodings UTF 9 and UTF 18 Adoption editSee also UTF 8 Adoption Unicode in the form of UTF 8 has been the most common encoding for the World Wide Web since 2008 74 It has near universal adoption and much of the non UTF 8 content is found in other Unicode encodings e g UTF 16 As of 2024 update UTF 8 accounts for on average 97 8 of all web pages and 987 of the top 1 000 highest ranked web pages 75 Although many pages only use ASCII characters to display content UTF 8 was designed with 8 bit ASCII as a subset and almost no websites now declare their encoding to only be ASCII instead of UTF 8 76 Over a third of the languages tracked have 100 UTF 8 use All internet protocols maintained by Internet Engineering Task Force e g FTP 77 have required support for UTF 8 since the publication of RFC 2277 in 1998 which specified that all IETF protocols MUST be able to use the UTF 8 charset 78 Operating systems edit Unicode has become the dominant scheme for the internal processing and storage of text Although a great deal of text is still stored in legacy encodings Unicode is used almost exclusively for building new information processing systems Early adopters tended to use UCS 2 the fixed length two byte obsolete precursor to UTF 16 and later moved to UTF 16 the variable length current standard as this was the least disruptive way to add support for non BMP characters The best known such system is Windows NT and its descendants 2000 XP Vista 7 8 10 and 11 which uses UTF 16 as the sole internal character encoding The Java and NET bytecode environments macOS and KDE also use it for internal representation Partial support for Unicode can be installed on Windows 9x through the Microsoft Layer for Unicode UTF 8 originally developed for Plan 9 79 has become the main storage encoding on most Unix like operating systems though others are also used by some libraries because it is a relatively easy replacement for traditional extended ASCII character sets UTF 8 is also the most common Unicode encoding used in HTML documents on the World Wide Web Multilingual text rendering engines which use Unicode include Uniscribe and DirectWrite for Microsoft Windows ATSUI and Core Text for macOS and Pango for GTK and the GNOME desktop Input methods edit Main article Unicode input Because keyboard layouts cannot have simple key combinations for all characters several operating systems provide alternative input methods that allow access to the entire repertoire ISO IEC 14755 80 which standardises methods for entering Unicode characters from their code points specifies several methods There is the Basic method where a beginning sequence is followed by the hexadecimal representation of the code point and the ending sequence There is also a screen selection entry method specified where the characters are listed in a table on a screen such as with a character map program Online tools for finding the code point for a known character include Unicode Lookup 81 by Jonathan Hedley and Shapecatcher 82 by Benjamin Milde In Unicode Lookup one enters a search key e g fractions and a list of corresponding characters with their code points is returned In Shapecatcher based on Shape context one draws the character in a box and a list of characters approximating the drawing with their code points is returned Email edit Main article Unicode and email MIME defines two different mechanisms for encoding non ASCII characters in email depending on whether the characters are in email headers such as the Subject or in the text body of the message in both cases the original character set is identified as well as a transfer encoding For email transmission of Unicode the UTF 8 character set and the Base64 or the Quoted printable transfer encoding are recommended depending on whether much of the message consists of ASCII characters The details of the two different mechanisms are specified in the MIME standards and generally are hidden from users of email software The IETF has defined 83 84 a framework for internationalized email using UTF 8 and has updated 85 86 87 88 several protocols in accordance with that framework The adoption of Unicode in email has been very slow citation needed Some East Asian text is still encoded in encodings such as ISO 2022 and some devices such as mobile phones citation needed still cannot correctly handle Unicode data Support has been improving however Many major free mail providers such as Yahoo Mail Gmail and Outlook com support it Web edit Main article Unicode and HTML All W3C recommendations have used Unicode as their document character set since HTML 4 0 Web browsers have supported Unicode especially UTF 8 for many years There used to be display problems resulting primarily from font related issues e g v6 and older of Microsoft Internet Explorer did not render many code points unless explicitly told to use a font that contains them 89 Although syntax rules may affect the order in which characters are allowed to appear XML including XHTML documents by definition 90 comprise characters from most of the Unicode code points with the exception of FFFE or FFFF most of the C0 control codes the permanently unassigned code points D800 DFFF HTML characters manifest either directly as bytes according to the document s encoding if the encoding supports them or users may write them as numeric character references based on the character s Unicode code point For example the references amp 916 amp 1049 amp 1511 amp 1605 amp 3671 amp 12354 amp 21494 amp 33865 and amp 47568 or the same numeric values expressed in hexadecimal with amp x as the prefix should display on all browsers as D J ק م 7 あ 叶 葉 and 말 When specifying URIs for example as URLs in HTTP requests non ASCII characters must be percent encoded Fonts edit Main article Unicode font Unicode is not in principle concerned with fonts per se seeing them as implementation choices 91 Any given character may have many allographs from the more common bold italic and base letterforms to complex decorative styles A font is Unicode compliant if the glyphs in the font can be accessed using code points defined in The Unicode Standard 92 The standard does not specify a minimum number of characters that must be included in the font some fonts have quite a small repertoire Free and retail fonts based on Unicode are widely available since TrueType and OpenType support Unicode and Web Open Font Format WOFF and WOFF2 is based on those These font formats map Unicode code points to glyphs but OpenType and TrueType font files are restricted to 65 535 glyphs Collection files provide a gap mode mechanism for overcoming this limit in a single font file Each font within the collection still has the 65 535 limit however A TrueType Collection file would typically have a file extension of ttc Thousands of fonts exist on the market but fewer than a dozen fonts sometimes described as pan Unicode fonts attempt to support the majority of Unicode s character repertoire Instead Unicode based fonts typically focus on supporting only basic ASCII and particular scripts or sets of characters or symbols Several reasons justify this approach applications and documents rarely need to render characters from more than one or two writing systems fonts tend to demand resources in computing environments and operating systems and applications show increasing intelligence in regard to obtaining glyph information from separate font files as needed i e font substitution Furthermore designing a consistent set of rendering instructions for tens of thousands of glyphs constitutes a monumental task such a venture passes the point of diminishing returns for most typefaces Newlines edit Unicode partially addresses the newline problem that occurs when trying to read a text file on different platforms Unicode defines a large number of characters that conforming applications should recognize as line terminators In terms of the newline Unicode introduced U 2028 LINE SEPARATOR and U 2029 PARAGRAPH SEPARATOR This was an attempt to provide a Unicode solution to encoding paragraphs and lines semantically potentially replacing all of the various platform solutions In doing so Unicode does provide a way around the historical platform dependent solutions Nonetheless few if any Unicode solutions have adopted these Unicode line and paragraph separators as the sole canonical line ending characters However a common approach to solving this issue is through newline normalization This is achieved with the Cocoa text system in Mac OS X and also with W3C XML and HTML recommendations In this approach every possible newline character is converted internally to a common newline which one does not really matter since it is an internal operation just for rendering In other words the text system can correctly treat the character as a newline regardless of the input s actual encoding Issues editCharacter unification edit Han unification edit Main article Han unification The Ideographic Research Group IRG is tasked with advising the Consortium and ISO regarding Han unification or Unihan especially the further addition of CJK unified and compatibility ideographs to the repertoire The IRG is composed of experts from each region that has historically used Chinese characters However despite the deliberation within the committee Han unification has consistently been one of the most contested aspects of The Unicode Standard since the genesis of the project 93 Existing character set standards such as the Japanese JIS X 0208 encoded by Shift JIS defined unification criteria meaning rules for determining when a variant Chinese character is to be considered a handwriting font difference and thus unified versus a spelling difference to be encoded separately Unicode s character model for CJK characters was based on the unification criteria used by JIS X 0208 as well as those developed by the Association for a Common Chinese Code in China 94 Due to the standard s principle of encoding semantic instead of stylistic variants Unicode has received criticism for not assigning code points to certain rare and archaic kanji variants possibly complicating processing of ancient and uncommon Japanese names Since it places particular emphasis on Chinese Japanese and Korean sharing many characters in common Han unification is also sometimes perceived as treating the three as the same thing 95 Less frequently used alternative encodings exist often predating Unicode with character models differing from this paradigm aimed at preserving the various stylistic differences between regional and or nonstandard character forms One example is the TRON Code favored by some users for handling historical Japanese text though not widely adopted among the Japanese public Another is the CCCII encoding adopted by library systems in Hong Kong Taiwan and the United States These have their own drawbacks in general use leading to the Big5 encoding introduced in 1984 four years after CCCII having become more common than CCCII outside of library systems 96 Although work at Apple based on Research Libraries Group s CJK Thesaurus which was used to maintain the EACC variant of CCCII was one of the direct predecessors of Unicode s Unihan set Unicode adopted the JIS style unification model 94 The earliest version of Unicode had a repertoire of fewer than 21 000 Han characters largely limited to those in relatively common modern usage As of version 15 1 the standard now encodes more than 97 000 Han characters and work is continuing to add thousands more largely historical and dialectal variant characters used throughout the Sinosphere Modern typefaces provide a means to address some of the practical issues in depicting unified Han characters with various regional graphical representations The locl OpenType table allows a renderer to select a different glyph for each code point based on the text locale 97 The Unicode variation sequences can also provide in text annotations for a desired glyph selection this requires registration of the specific variant in the Ideographic Variation Database Italic or cursive characters in Cyrillic edit nbsp Various Cyrillic characters shown with upright oblique and italic alternate forms If the appropriate glyphs for characters in the same script differ only in the italic Unicode has generally unified them as can be seen in the comparison among a set of seven characters italic glyphs as typically appearing in Russian traditional Bulgarian Macedonian and Serbian texts at right meaning that the differences are displayed through smart font technology or manually changing fonts The same OpenType locl technique is used 98 Localised case pairs edit For use in the Turkish alphabet and Azeri alphabet Unicode includes a separate dotless lowercase I i and a dotted uppercase I I However the usual ASCII letters are used for the lowercase dotted I and the uppercase dotless I matching how they are handled in the earlier ISO 8859 9 As such case insensitive comparisons for those languages have to use different rules than case insensitive comparisons for other languages using the Latin script 99 By contrast the Icelandic eth d the barred D đ and the retroflex D ɖ which usually note 3 look the same in uppercase Đ are given the opposite treatment and encoded separately in both letter cases in contrast to the earlier ISO 6937 which unifies the uppercase forms Although it allows for case insensitive comparison without needing to know the language of the text this approach also has issues requiring security measures relating to homoglyph attacks 100 Diacritics on lowercase I edit nbsp Localised forms of the letter i I with acute accent Whether the lowercase letter I is expected to retain its tittle when a diacritic applies also depends on local conventions Security edit Unicode has a large number of homoglyphs many of which look very similar or identical to ASCII letters Substitution of these can make an identifier or URL that looks correct but directs to a different location than expected 101 Additionally homoglyphs can also be used for manipulating the output of natural language processing NLP systems 102 Mitigation requires disallowing these characters displaying them differently or requiring that they resolve to the same identifier 103 all of this is complicated due to the huge and constantly changing set of characters 104 105 A security advisory was released in 2021 by two researchers one from the University of Cambridge and the other from the University of Edinburgh in which they assert that the BiDi marks can be used to make large sections of code do something different from what they appear to do The problem was named Trojan Source 106 In response code editors started highlighting marks to indicate forced text direction changes 107 Mapping to legacy character sets edit Unicode was designed to provide code point by code point round trip format conversion to and from any preexisting character encodings so that text files in older character sets can be converted to Unicode and then back and get back the same file without employing context dependent interpretation That has meant that inconsistent legacy architectures such as combining diacritics and precomposed characters both exist in Unicode giving more than one method of representing some text This is most pronounced in the three different encoding forms for Korean Hangul Since version 3 0 any precomposed characters that can be represented by a combined sequence of already existing characters can no longer be added to the standard to preserve interoperability between software using different versions of Unicode Injective mappings must be provided between characters in existing legacy character sets and characters in Unicode to facilitate conversion to Unicode and allow interoperability with legacy software Lack of consistency in various mappings between earlier Japanese encodings such as Shift JIS or EUC JP and Unicode led to round trip format conversion mismatches particularly the mapping of the character JIS X 0208 1 33 WAVE DASH heavily used in legacy database data to either U FF5E FULLWIDTH TILDE in Microsoft Windows or U 301C WAVE DASH other vendors 108 Some Japanese computer programmers objected to Unicode because it requires them to separate the use of U 005C REVERSE SOLIDUS backslash and U 00A5 YEN SIGN which was mapped to 0x5C in JIS X 0201 and a lot of legacy code exists with this usage 109 This encoding also replaces tilde 0x7E with macron now 0xAF The separation of these characters exists in ISO 8859 1 from long before Unicode Indic scripts edit Further information Tamil All Character Encoding Indic scripts such as Tamil and Devanagari are each allocated only 128 code points matching the ISCII standard The correct rendering of Unicode Indic text requires transforming the stored logical order characters into visual order and the forming of ligatures also known as conjuncts out of components Some local scholars argued in favor of assignments of Unicode code points to these ligatures going against the practice for other writing systems though Unicode contains some Arabic and other ligatures for backward compatibility purposes only 110 111 112 Encoding of any new ligatures in Unicode will not happen in part because the set of ligatures is font dependent and Unicode is an encoding independent of font variations The same kind of issue arose for the Tibetan script in 2003 when the Standardization Administration of China proposed encoding 956 precomposed Tibetan syllables 113 but these were rejected for encoding by the relevant ISO committee ISO IEC JTC 1 SC 2 114 Thai alphabet support has been criticized for its ordering of Thai characters The vowels e ae o i i that are written to the left of the preceding consonant are in visual order instead of phonetic order unlike the Unicode representations of other Indic scripts This complication is due to Unicode inheriting the Thai Industrial Standard 620 which worked in the same way and was the way in which Thai had always been written on keyboards This ordering problem complicates the Unicode collation process slightly requiring table lookups to reorder Thai characters for collation 95 Even if Unicode had adopted encoding according to spoken order it would still be problematic to collate words in dictionary order E g the word aesdng sa dɛːŋ perform starts with a consonant cluster sd with an inherent vowel for the consonant s the vowel ae in spoken order would come after the d but in a dictionary the word is collated as it is written with the vowel following the s Combining characters edit Main article Combining character See also Unicode normalization Normalization Characters with diacritical marks can generally be represented either as a single precomposed character or as a decomposed sequence of a base letter plus one or more non spacing marks For example ḗ precomposed e with macron and acute above and e e followed by the combining macron above and combining acute above should be rendered identically both appearing as an e with a macron and acute accent but in practice their appearance may vary depending upon what rendering engine and fonts are being used to display the characters Similarly underdots as needed in the romanization of Indic will often be placed incorrectly citation needed Unicode characters that map to precomposed glyphs can be used in many cases thus avoiding the problem but where no precomposed character has been encoded the problem can often be solved by using a specialist Unicode font such as Charis SIL that uses Graphite OpenType gsub or AAT technologies for advanced rendering features Anomalies edit Main article Unicode alias names and abbreviations The Unicode Standard has imposed rules intended to guarantee stability 115 Depending on the strictness of a rule a change can be prohibited or allowed For example a name given to a code point cannot and will not change But a script property is more flexible by Unicode s own rules In version 2 0 Unicode changed many code point names from version 1 At the same moment Unicode stated that thenceforth an assigned name to a code point would never change This implies that when mistakes are published these mistakes cannot be corrected even if they are trivial as happened in one instance with the spelling BRAKCET for BRACKET in a character name In 2006 a list of anomalies in character names was first published and as of June 2021 there were 104 characters with identified issues 116 for example U 034F COMBINING GRAPHEME JOINER Does not join graphemes 116 U 2118 SCRIPT CAPITAL P This is a small letter The capital is U 1D4AB 𝒫 MATHEMATICAL SCRIPT CAPITAL P 117 U A015 ꀕ YI SYLLABLE WU This is not a Yi syllable but a Yi iteration mark U FE18 PRESENTATION FORM FOR VERTICAL RIGHT WHITE LENTICULAR BRAKCET bracket is spelled incorrectly 118 Spelling errors are resolved by using Unicode alias names While Unicode defines the script designator name to be Phags Pa in that script s character names a hyphen is added U A840 ꡀ PHAGS PA LETTER KA 119 120 This however is not an anomaly but the rule hyphens are replaced by underscores in script designators 119 See also editComparison of Unicode encodings International Components for Unicode ICU now as ICU TC a part of Unicode List of binary codes List of Unicode characters List of XML and HTML character entity references Lotus Multi Byte Character Set LMBCS a parallel development with similar intentions Open source Unicode typefaces Religious and political symbols in Unicode Standards related to Unicode Unicode symbols Universal Coded Character SetNotes edit Sometimes abbreviated as TUS 1 2 A Unicode Standard Annex UAX forms an integral part of The Unicode Standard but is published as a separate document 1 Rarely the uppercase Icelandic eth may instead be written in an insular style Ꝺ with the crossbar positioned on the stem particularly if it needs to be distinguished from the uppercase retroflex D see African Reference Alphabet References edit The Unicode Standard Version 15 1 0 South San Francisco CA The Unicode Consortium 2023 ISBN 978 1 936213 33 7 Unicode Technical Report 28 Unicode 3 2 Unicode Consortium 2002 03 27 Retrieved 2022 06 23 Jenkins John H 2021 08 26 Unicode Standard Annex 45 U source Ideographs Unicode Consortium Retrieved 2022 06 23 2 2 The Source Field Unicode Character Count V15 1 Unicode Archived from the original on 2023 10 09 Retrieved 2023 09 12 Emoji Counts v15 1 Unicode Archived from the original on 2023 09 28 Retrieved 2023 09 12 The Unicode Standard A Technical Introduction Retrieved 2010 03 16 Unicode Bulldog Award Unicode Archived from the original on 2023 11 11 a b c d e Becker Joseph D 1998 09 10 1988 08 29 Unicode 88 PDF Unicode Consortium Archived PDF from the original on 2016 11 25 Retrieved 2016 10 25 In 1978 the initial proposal for a set of Universal Signs was made by Bob Belleville at Xerox PARC Many persons contributed ideas to the development of a new encoding design Beginning in 1980 these efforts evolved into the Xerox Character Code Standard XCCS by the present author a multilingual encoding that has been maintained by Xerox as an internal corporate standard since 1982 through the efforts of Ed Smura Ron Pellar and others Unicode arose as the result of eight years of working experience with XCCS Its fundamental differences from XCCS were proposed by Peter Fenwick and Dave Opstad pure 16 bit codes and by Lee Collins ideographic character unification Unicode retains the many features of XCCS whose utility has been proved over the years in an international line of communication multilingual system products Summary Narrative Unicode 2006 08 31 Retrieved 2010 03 15 History of Unicode Release and Publication Dates Unicode Retrieved 2023 03 20 Searle Stephen J Unicode Revisited Retrieved 2013 01 18 a b The Unicode Consortium Members Retrieved 2024 02 12 Unicode FAQ Retrieved 2020 04 02 Supported Scripts Unicode Retrieved 2022 09 16 Roadmap to the BMP Unicode Consortium Retrieved 2018 07 30 Roadmaps to Unicode Unicode Archived from the original on 2023 12 08 script encoding initiative Berkeley Linguistics Archived from the original on 2023 03 25 About The Script Encoding Initiative The Unicode Consortium Retrieved 2012 06 04 Unicode 6 1 Paperback Available announcements at unicode org Retrieved 2012 05 30 Unicode 15 0 0 Unicode Retrieved 2023 09 12 Emoji Counts v15 0 Unicode Retrieved 2023 09 12 Enumerated Versions of The Unicode Standard Retrieved 2016 06 21 Unicode version 1 0 1991 1 0 0 UnicodeData txt reconstructed 2004 Retrieved 2010 03 16 Unicode Data 1 0 1 Retrieved 2010 03 16 Unicode version 1 1 Unicode Data 1995 Retrieved 2010 03 16 Unicode version 2 0 0 Unicode Data 2 0 14 Retrieved 2010 03 16 a b Unicode version 2 1 0 Unicode Data 2 1 2 Retrieved 2010 03 16 Unicode version 3 0 0 Unicode Data 3 0 0 Retrieved 2023 10 02 Unicode version 3 1 0 Unicode Data 3 1 0 Retrieved 2023 10 02 Unicode version 3 2 0 Unicode Data 3 2 0 Retrieved 2023 10 02 Unicode version 4 0 0 Unicode Data 4 0 0 Retrieved 2023 10 02 Unicode Data 4 1 0 Retrieved 2010 03 16 Named Sequences 4 1 0 Retrieved 2010 03 16 Unicode Data 5 0 0 Retrieved 2010 03 17 Unicode Data 5 1 0 Retrieved 2010 03 17 Unicode Data 5 2 0 Retrieved 2010 03 17 Unicode Data 6 0 0 Retrieved 2010 10 11 Unicode 6 0 Emoji List emojipedia org Retrieved 2022 09 21 Unicode Data 6 1 0 Retrieved 2012 01 31 Unicode Data 6 2 0 Retrieved 2012 09 26 Unicode Data 6 3 0 Retrieved 2013 09 30 Unicode Data 7 0 0 Retrieved 2014 06 15 Unicode Data 8 0 0 Retrieved 2015 06 17 Unicode 8 0 0 Unicode Consortium Retrieved 2015 06 17 Unicode 9 0 0 Unicode Consortium Retrieved 2016 06 21 Unicode Data 9 0 0 Retrieved 2016 06 21 Lobao Martim 2016 06 07 These Are The Two Emoji That Weren t Approved For Unicode 9 But Which Google Added To Android Anyway Android Police Retrieved 2016 09 04 Unicode 10 0 0 Unicode Consortium Retrieved 2017 06 20 The Unicode Standard Version 11 0 0 Appendix C PDF Unicode Consortium Retrieved 2018 06 11 The Unicode Standard Version 12 0 0 Appendix C PDF Unicode Consortium Retrieved 2019 03 05 Unicode Version 12 1 released in support of the Reiwa Era The Unicode Blog Retrieved 2019 05 07 Unicode 13 0 0 Announcing The Unicode Standard Version 13 0 The Unicode Blog Retrieved 2020 03 11 The Unicode Standard Version 13 0 Core Specification Appendix C PDF Unicode Consortium Retrieved 2020 03 11 Unicode 14 0 0 Announcing The Unicode Standard Version 14 0 Unicode 15 0 0 Unicode 15 1 0 Proposed New Characters The Pipeline Unicode 2023 09 12 Retrieved 2023 09 13 Unicode Version 16 0 emojipedia org Retrieved 2023 09 13 Glossary of Unicode Terms Retrieved 2010 03 16 2 4 Code Points and Characters The Unicode Standard Version 15 1 Core Specification PDF 2023 p 29 3 4 Characters and Encoding The Unicode Standard Version 15 1 PDF 2023 p 88 Re Origin of the U nnnn notation Unicode Mail List Archive Mailing list 2005 11 08 Appendix A Notational Conventions PDF The Unicode Standard Unicode Consortium September 2023 a b Unicode Character Encoding Stability Policy Retrieved 2010 03 16 Properties PDF Retrieved 2023 09 12 Unicode Character Encoding Model Retrieved 2023 09 12 Unicode Named Sequences Retrieved 2022 09 16 Unicode Name Aliases Retrieved 2010 03 16 JanaSanskritSans Archived from the original on 2011 07 16 CWA 13873 2000 Multilingual European Subsets in ISO IEC 10646 1 CEN Workshop Agreement 13873 Kuhn Markus 1998 Multilingual European Character Set 2 MES 2 Rationale University of Cambridge Retrieved 2023 03 20 DIN 91379 2022 08 Characters and defined character sequences in Unicode for the electronic processing of names and data exchange in Europe with CD ROM Beuth Verlag Retrieved 2022 08 21 UTF 8 UTF 16 UTF 32 amp BOM Unicode org FAQ Retrieved 2016 12 12 The Unicode Standard Version 6 2 The Unicode Consortium 2013 p 561 ISBN 978 1 936213 08 5 Davis Mark 2008 05 05 Moving to Unicode 5 1 Official Google Blog Retrieved 2021 02 19 Usage Survey of Character Encodings broken down by Ranking W3Techs Retrieved 2023 01 16 Usage Statistics and Market Share of US ASCII for Websites October 2021 W3Techs Retrieved 2020 11 01 B Curtin July 1999 Internationalization of the File Transfer Protocol doi 10 17487 RFC2640 RFC 2640 Retrieved 2022 08 17 H Alvestrand January 1998 IETF Policy on Character Sets and Languages doi 10 17487 RFC2277 BCP 18 RFC 2277 Retrieved 2022 08 17 Pike Rob 2003 04 30 UTF 8 history ISO IEC JTC1 SC 18 WG 9 N PDF Retrieved 2012 06 04 Hedley Jonathan 2009 Unicode Lookup Milde Benjamin 2011 Unicode Character Recognition J Klensin Y Ko July 2007 Overview and Framework for Internationalized Email doi 10 17487 RFC4952 RFC 4952 Retrieved 2022 08 17 J Klensin Y Ko February 2012 Overview and Framework for Internationalized Email doi 10 17487 RFC6530 RFC 6530 Retrieved 2022 08 17 J Yao W Mao February 2012 SMTP Extension for Internationalized Email doi 10 17487 RFC6531 RFC 6531 Retrieved 2022 08 17 A Yang S Steele N Freed February 2012 Internationalized Email Headers doi 10 17487 RFC6532 RFC 6532 Retrieved 2022 08 17 C Newman A Gulbrandsen A Melnikov June 2008 Internet Message Access Protocol Internationalization doi 10 17487 RFC5255 RFC 5255 Retrieved 2022 08 17 R Gellens C Newman February 2010 POP3 Support for UTF 8 doi 10 17487 RFC5721 RFC 5721 Retrieved 2022 08 17 Wood Alan Setting up Windows Internet Explorer 5 5 5 and 6 for Multilingual and Unicode Support Alan Wood Retrieved 2012 06 04 Extensible Markup Language XML 1 1 Second Edition Retrieved 2013 11 01 Bigelow Charles Holmes Kris September 1993 The design of a Unicode font PDF Electronic Publishing 6 3 292 Fonts and keyboards Unicode Consortium 2017 06 28 Retrieved 2019 10 13 A Brief History of Character Codes Steven J Searle originally written 1999 last updated 2004 a b Appendix E Han Unification History PDF The Unicode Standard Version 15 0 Core Specification Unicode Consortium 2022 a b Topping Suzanne 2013 06 25 The secret life of Unicode IBM Archived from the original on 2013 06 25 Retrieved 2023 03 20 Wittern Christian 1995 05 01 Chinese character codes an update International Research Institute for Zen Buddhism Hanazono University Archived from the original on 2004 10 12 Noto CJK fonts Noto Fonts 2023 02 18 Select this deployment format if your system supports variable fonts and you prefer to use only one language but also want full character coverage or the ability to language tag text to use glyphs that are appropriate for the other languages this requires an app that supports language tagging and the OpenType locl GSUB feature Preuss Ingo OpenType Feature locl Localized Forms preusstype com Case Folding Properties Unicode Character Database Unicode Consortium 2023 05 12 confusablesSummary txt Unicode Security Mechanisms for UTS 39 Unicode Consortium 2023 08 11 UTR 36 Unicode Security Considerations Unicode Boucher Nicholas Shumailov Ilia Anderson Ross Papernot Nicolas 2022 Bad Characters Imperceptible NLP Attacks 2022 IEEE Symposium on Security and Privacy SP San Francisco CA US IEEE pp 1987 2004 arXiv 2106 09898 doi 10 1109 SP46214 2022 9833641 ISBN 978 1 66541 316 9 S2CID 235485405 Engineering Spotify 2013 06 18 Creative usernames and Spotify account hijacking Spotify Engineering Retrieved 2023 04 15 Wheeler David A 2020 Countermeasures Initial Analysis of Underhanded Source Code 4 1 UTR 36 Unicode Security Considerations Unicode Retrieved 2022 06 27 Boucher Nicholas Anderson Ross Trojan Source Invisible Vulnerabilities PDF Retrieved 2021 11 02 Visual Studio Code October 2021 code visualstudio com Retrieved 2021 11 11 AFII contribution about WAVE DASH An Unicode vendor specific character table for japanese 2011 04 22 Archived from the original on 2011 04 22 Retrieved 2019 05 20 ISO 646 Problem Section 4 4 3 5 of Introduction to I18n Tomohiro Kubota 2001 Arabic Presentation Forms A PDF Retrieved 2010 03 20 Arabic Presentation Forms B PDF Retrieved 2010 03 20 Alphabetic Presentation Forms PDF Retrieved 2010 03 20 Proposal on Tibetan BrdaRten Characters Encoding for ISO IEC 10646 in BMP PDF 2002 12 02 Umamaheswaran V S 2003 11 07 Resolutions of WG 2 meeting 44 PDF Resolution M44 20 Character Encoding Stability Unicode Archived from the original on 2024 01 01 a b Unicode Technical Note 27 Known Anomalies in Unicode Character Names Unicode 2021 06 14 Unicode chart actually this has the form of a lowercase calligraphic p despite its name PDF Misspelling of BRACKET in character name is a known defect PDF a b Unicode Standard Annex 24 Unicode Script Property The Unicode Consortium 2021 2 2 Relation to ISO 15924 Codes Retrieved 2022 04 29 Scripts 15 1 0 txt The Unicode Consortium 2023 Retrieved 2023 09 12 Further reading editJulie D Allen The Unicode Standard Version 6 0 The Unicode Consortium Mountain View 2011 ISBN 9781936213016 Unicode 6 0 0 The Complete Manual of Typography James Felici Adobe Press 1st edition 2002 ISBN 0 321 12730 7 The Unicode Standard Version 3 0 The Unicode Consortium Addison Wesley Longman Inc April 2000 ISBN 0 201 61633 5 The Unicode Standard Version 4 0 The Unicode Consortium Addison Wesley Professional 27 August 2003 ISBN 0 321 18578 1 The Unicode Standard Version 5 0 Fifth Edition The Unicode Consortium Addison Wesley Professional 27 October 2006 ISBN 0 321 48091 0 gt Unicode Demystified A Practical Programmer s Guide to the Encoding Standard Richard Gillam Addison Wesley Professional 1st edition 2002 ISBN 0 201 70052 2 Unicode Explained Jukka K Korpela O Reilly 1st edition 2006 ISBN 0 596 10121 X Unicode A Primer Tony Graham M amp T books 2000 ISBN 0 7645 4625 2 Haralambous Yannis Martin Durst 2019 Unicode from a Linguistic Point of View In Haralambous Yannis ed Proceedings of Graphemics in the 21st Century Brest 2018 Brest Fluxus Editions pp 167 183 doi 10 36824 2018 graf hara1 ISBN 978 2 9570549 1 6 External links editUnicode at Wikipedia s sister projects nbsp Media from Commons nbsp Textbooks from Wikibooks Unicode Inc Unicode Technical Site The Unicode Standard Unicode Character Code Charts Unicode Character Name Index Alan Wood s Unicode Resources contains lists of word processors with Unicode capability fonts and characters are grouped by type characters are presented in lists not grids Unicode at Curlie Unicode BMP Fallback Font displays the Unicode 6 1 value of any character in a document including in the Private Use Area rather than the glyph itself The World s Writing Systems all 294 known writing systems with their Unicode status 131 not yet encoded as of 2023 update Retrieved from https en wikipedia org w index php title Unicode amp oldid 1224336767 14 0, wikipedia, wiki, book, books, library,

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