UNICODE is a computing industry standard for the consistent encoding
, representation, and handling of text expressed in most of the
world's writing systems . Developed in conjunction with the Universal
Coded Character Set (UCS) standard and published as _The Unicode
Standard_, the latest version of
Unicode contains a repertoire of
136,755 characters covering 139 modern and historic scripts , as well
as multiple symbol sets.
The standard consists of a set of code charts for visual reference,
an encoding method and set of standard character encodings , a set of
reference data files , and a number of related items, such as
character properties, rules for normalization , decomposition,
collation , rendering, and bidirectional display order (for the
correct display of text containing both right-to-left scripts, such as
Arabic and Hebrew , and left-to-right scripts). As of June 2017 , the
most recent version is _
Unicode 10.0_. The standard is maintained by
Unicode Consortium .
Unicode's success at unifying character sets has led to its
widespread and predominant use in the internationalization and
localization of computer software . The standard has been implemented
in many recent technologies, including modern operating systems , XML
, Java (and other programming languages), and the
.NET Framework .
Unicode can be implemented by different character encodings . The
Unicode standard defines
UTF-16 , and
UTF-32 , and several
other encodings are in use. The most commonly used encodings are UTF-8
UTF-16 and UCS-2, a precursor of
UTF-8, the most widely used by websites, uses one byte for the first
128 code points, and up to 4 bytes for other characters. The first 128
Unicode code points are the
ASCII characters; so an
ASCII text is a
UCS-2 simply uses two bytes (16 bits) for each character but can only
encode the first 65,536 code points, the so-called Basic Multilingual
Plane . With 1,114,112 code points on 17 planes being possible, and
with over 120,000 code points defined so far, many
are beyond the reach of UCS-2. Therefore,
UCS-2 is obsolete, though
still widely used in software.
UTF-16 extends UCS-2, by using the same
16-bit encoding as
UCS-2 for the Basic Multilingual Plane, and a
4-byte encoding for the other planes. Therefore, a
UCS-2 text is a
UTF-32 (also referred to as UCS-4) uses four bytes for each
character. Like UCS-2, the number of bytes per character is fixed,
facilitating character indexing; but unlike UCS-2,
UTF-32 is able to
Unicode code points. However, because each character uses
UTF-32 takes significantly more space than other
encodings, and is not widely used.
* 1 Origin and development
* 1.1 History
* 1.2 Architecture and terminology
Code point planes and blocks
* 1.2.2 General
* 1.2.3 Abstract characters
* 1.4 Versions
* 1.5 Scripts covered
* 2 Mapping and encodings
Unicode Transformation Format and Universal Coded Character
* 2.2 Ready-made versus composite characters
* 2.3 Ligatures
* 2.4 Standardized subsets
* 3 Adoption
* 3.1 Operating systems
* 3.2 Input methods
* 3.4 Web
* 3.5 Fonts
* 3.6 Newlines
* 4 Issues
* 4.1 Philosophical and completeness criticisms
* 4.2 Mapping to legacy character sets
* 4.3 Indic scripts
* 4.4 Combining characters
* 4.5 Anomalies
* 5 See also
* 6 References
* 7 Further reading
* 8 External links
ORIGIN AND DEVELOPMENT
Unicode has the explicit aim of transcending the limitations of
traditional character encodings, such as those defined by the ISO 8859
standard, which find wide usage in various countries of the world but
remain largely incompatible with each other. Many traditional
character encodings share a common problem in that they allow
bilingual computer processing (usually using Latin characters and the
local script), but not multilingual computer processing (computer
processing of arbitrary scripts mixed with each other).
Unicode, in intent, encodes the underlying characters—graphemes and
grapheme-like units—rather than the variant glyphs (renderings) for
such characters. In the case of Chinese characters , this sometimes
leads to controversies over distinguishing the underlying character
from its variant glyphs (see
Han unification ).
In text processing,
Unicode takes the role of providing a unique
_code point_—a number , not a glyph—for each character. In other
Unicode represents a character in an abstract way and leaves
the visual rendering (size, shape, font , or style) to other software,
such as a web browser or word processor . This simple aim becomes
complicated, however, because of concessions made by Unicode's
designers in the hope of encouraging a more rapid adoption of Unicode.
The first 256 code points were made identical to the content of
ISO-8859-1 so as to make it trivial to convert existing western text.
Many essentially identical characters were encoded multiple times at
different code points to preserve distinctions used by legacy
encodings and therefore, allow conversion from those encodings to
Unicode (and back) without losing any information. For example, the
"fullwidth forms " section of code points encompasses a full Latin
alphabet that is separate from the main Latin alphabet section because
in Chinese, Japanese, and Korean (
CJK ) fonts, these Latin characters
are rendered at the same width as
CJK ideographs , rather than at half
the width. For other examples, see duplicate characters in
Based on experiences with the
Xerox Character Code Standard (XCCS)
since 1980, the origins of
Unicode date to 1987, when Joe Becker from
Xerox and Lee Collins and Mark Davis from Apple started investigating
the practicalities of creating a universal character set. With
additional input from Peter Fenwick and Dave Opstad, Joe Becker
published a draft proposal for an "international/multilingual text
character encoding system in August 1988, tentatively called Unicode".
He explained that "he name 'Unicode' is intended to suggest a unique,
unified, universal encoding".
In this document, entitled _
Unicode 88_, Becker outlined a 16-bit
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.
His original 16-bit design was based on the assumption that only
those scripts and characters in modern use would need to be encoded:
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 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 Unicodes.
In early 1989, the
Unicode working group expanded to include Ken
Whistler and Mike Kernaghan of Metaphor, Karen Smith-Yoshimura and
Joan Aliprand of RLG , and Glenn Wright of
Sun Microsystems , and in
1990, Michel Suignard and Asmus Freytag from
Microsoft and Rick
NeXT joined the group. By the end of 1990, most of the work
on mapping existing character encoding standards had been completed,
and a final review draft of
Unicode was ready.
Unicode Consortium was incorporated in California on January 3,
1991, and in October 1991, the first volume of the
was published. The second volume, covering 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
Unicode codespace to over a million code points, which
allowed for the encoding of many historic scripts (e.g., Egyptian
Hieroglyphs ) and thousands of rarely used or obsolete characters that
had not been anticipated as needing encoding. Among the characters not
originally intended for
Unicode are rarely used
Kanji or Chinese
characters, many of which are part of personal and place names, making
them rarely used, but much more essential than envisioned in the
original architecture of Unicode.
TrueType specification version 1.0 from 1992 used the
name _Apple Unicode_ instead of _Unicode_ for the Platform ID in the
ARCHITECTURE AND TERMINOLOGY
Unicode defines a codespace of 1,114,112 code points in the range
0hex to 10FFFFhex. Normally a
Unicode code point is referred to by
writing "U+" followed by its hexadecimal number. For code points in
Basic Multilingual Plane (BMP), four digits are used (e.g., U+0058
for the character LATIN CAPITAL LETTER X); for code points outside the
BMP, five or six digits are used, as required (e.g., U+E0001 for the
character LANGUAGE TAG and U+10FFFD for the character PRIVATE USE
Code Point Planes And Blocks
Unicode codespace is divided into seventeen _planes_, numbered 0
Unicode planes and used code point ranges
BASIC MULTILINGUAL PLANE
SUPPLEMENTARY MULTILINGUAL PLANE
SUPPLEMENTARY IDEOGRAPHIC PLANE
SUPPLEMENTARY SPECIAL-PURPOSE PLANE
SUPPLEMENTARY PRIVATE USE AREA PLANES
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 (_supplementary planes_) are
accessed as surrogate pairs in
UTF-16 and encoded in four bytes in
Within each plane, characters are allocated within named _blocks _ of
related characters. Although blocks are an arbitrary size, they are
always a multiple of 16 code points and often a multiple of 128 code
points. Characters required for a given script may be spread out over
several different blocks.
Each code point has a single General
Category property. The major
categories are denoted: Letter, Mark, Number, Punctuation, Symbol,
Separator and Other. Within these categories, there are subdivisions.
Category is not useful for every use, since legacy
encodings have used multiple characteristics per single code point.
Line feed (LF) in
ASCII is both a control and a
formatting separator; in
Unicode the General
Category is "Other,
Control". Often, other properties must be used to specify the
characteristics and behaviour of a code point. The possible General
Unicode Character Property )
CATEGORY MAJOR, MINOR
Ligatures containing uppercase followed by lowercase letters (e.g.,
ǋ , and
Mark, spacing combining
Number, decimal digit
All these, and only these, have Numeric Type = De
Numerals composed of letters or letterlike symbols (e.g., Roman
E.g., vulgar fractions , superscript and subscript digits
Includes "_" underscore
Includes several hyphen characters
Opening bracket characters
Closing bracket characters
Punctuation, initial quote
Opening quotation mark . Does not include the
quotation mark. May behave like Ps or Pe depending on usage
Punctuation, final quote
Closing quotation mark. May behave like Ps or Pe depending on usage
Includes the space, but not TAB , CR , or LF , which are Cc
Only U+2028 LINE SEPARATOR (LSEP)
Only U+2029 PARAGRAPH SEPARATOR (PSEP)
No name ,
Includes the soft hyphen , control characters to support
bi-directional text , and language tag characters
Not (but abstract)
No name ,
Other, private use
Not (but abstract)
Fixed 137,468 total: 6,400 in BMP , 131,068 in Planes 15–16
No name ,
Other, not assigned
No name ,
No name ,
* ^ "Table 4-4: General Category" (PDF). _The
Unicode Consortium. July 2017.
* ^ _A_ _B_ "Table 2-3: Types of code points" (PDF). _The Unicode
Unicode Consortium. July 2017.
* ^ _A_ _B_
Unicode Character Encoding Stability Policies: Property
Value Stability Stability policy: Some gc groups will never change.
gc=Nd corresponds with Numeric Type=De (decimal).
* ^ _A_ _B_ _C_ _D_ _E_ "Table 4-13: Construction of Code Point
Labels" (PDF). _The
Unicode Consortium. July 2017.
A _Code Point Label_ may be used to identify a nameless code point.
E.g. , . The Name remains blank, which can prevent inadvertently
replacing, in documentation, a Control Name with a true Control code.
Unicode also uses for .
Code points in the range U+D800–U+DBFF (1,024 code points) are
known as high-surrogate code points, and code points in the range
U+DC00–U+DFFF (1,024 code points) are known as low-surrogate code
points. A high-surrogate code point (also known as a leading
surrogate) followed by a low-surrogate code point (also known as a
trailing surrogate) together form a surrogate pair used in
represent 1,048,576 code points outside BMP. High and low surrogate
code points are not valid by themselves. Thus the range of code points
that are available for use as characters is U+0000–U+D7FF and
U+E000–U+10FFFF (1,112,064 code points). The value of these code
points (i.e., excluding surrogates) is sometimes referred to as the
character's scalar value.
Certain non-character code points are guaranteed never to be used for
encoding characters, although applications may make use of these code
points internally if they wish. There are sixty-six noncharacters:
U+FDD0–U+FDEF and any code point ending in the value FFFE or FFFF
(i.e., 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
Reserved code points are those code points which are available for
use as encoded characters, but are not yet defined as characters by
Private-use code points are considered to be assigned characters, but
they have no interpretation specified by the
Unicode standard so any
interchange of such characters requires an agreement between sender
and receiver on their interpretation. There are three private-use
areas in the
* Private Use Area: U+E000–U+F8FF (6,400 characters)
* Supplementary Private Use Area-A: U+F0000–U+FFFFD (65,534
* Supplementary Private Use Area-B: U+100000–U+10FFFD (65,534
Graphic characters are characters defined by
Unicode to have a
particular semantic, and either have a visible glyph shape or
represent a visible space. As of
Unicode 10.0 there are 136,537
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
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 153 format characters in
Sixty-five code points (U+0000–U+001F and U+007F–U+009F) are
reserved as control codes, and correspond to the C0 and C1 control
codes defined in ISO/IEC 6429. Of these U+0009 (Tab), U+000A (Line
Feed), and U+000D (Carriage Return) are widely used in Unicode-encoded
Graphic characters, format characters, control code characters, and
private use characters are known collectively as _assigned
The set of graphic and format characters defined by
Unicode does not
correspond directly to the repertoire of _abstract characters_ that is
representable under Unicode.
Unicode encodes characters by associating
an abstract character with a particular code point. 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,
Unicode maintains a list of uniquely named character sequences
for abstract characters that are not directly encoded in Unicode.
All graphic, format, and private use characters have a unique and
immutable name by which they may be identified. This immutability has
been guaranteed since
Unicode version 2.0 by the Name Stability
policy. In cases where the name is seriously defective and
misleading, or has a serious typographical error, a formal alias may
be defined, and applications are encouraged to use the formal alias 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.
Unicode Consortium is a nonprofit organization that coordinates
Unicode's development. Full members include most of the main computer
software and hardware companies with any interest in text-processing
Adobe Systems , Apple ,
Google , IBM , Microsoft
Oracle Corporation , and
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
Unicode is developed in conjunction with the International
Organization for Standardization and shares the character repertoire
ISO/IEC 10646 : the Universal Character Set.
Unicode and ISO/IEC
10646 function equivalently as character encodings, but _The Unicode
Standard_ contains much more information for implementers,
covering—in depth—topics such as bitwise encoding, collation and
Unicode Standard enumerates a multitude of character
properties, including those needed for supporting bidirectional text .
The two standards do use slightly different terminology.
The Consortium first published _The
Unicode Standard_ (ISBN
0-321-18578-1 ) in 1991 and continues to develop standards based on
that original work. The latest version of the standard,
was released in June 2017 and is available from the consortium's
website. The last of the major versions (versions x.0) to be published
in book form was
Unicode 5.0 (ISBN 0-321-48091-0 ), but since Unicode
6.0 the full text of the standard is no longer being published in book
form. In 2012, however, it was announced that only the core
Unicode version 6.1 would be made available as a
692-page print-on-demand paperback. Unlike the previous major version
printings of the Standard, the print-on-demand core specification does
not include any code charts or standard annexes, but the entire
standard, including the core specification, will still remain freely
available on the
Thus far, the following major and minor 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.
ISO/IEC 10646 EDITION
ISBN 0-201-56788-1 (Vol.1)
Initial repertoire covers these scripts: Arabic , Armenian ,
Devanagari , Georgian , Greek and
Coptic , Gujarati , Gurmukhi ,
Hangul , Hebrew ,
Hiragana , Kannada ,
Katakana , Lao , Latin , Malayalam , Oriya , Tamil , Telugu , Thai ,
and Tibetan .
ISBN 0-201-60845-6 (Vol.2)
The initial set of 20,902
CJK Unified Ideographs is defined.
Hangul syllables added to original set of 2,350
characters. Tibetan removed.
ISO/IEC 10646-1:1993 plus Amendments 5, 6 and 7
Original set of
Hangul syllables removed, and a new set of 11,172
Hangul syllables added at a new location. Tibetan added back in a new
location and with a different character repertoire. Surrogate
character mechanism defined, and Plane 15 and Plane 16 Private Use
ISO/IEC 10646-1:1993 plus Amendments 5, 6 and 7, as well as two
characters from Amendment 18
Euro sign and Object Replacement Character added.
Cherokee , Ethiopic , Khmer , Mongolian , Burmese ,
Ogham , Runic ,
Sinhala , Syriac ,
Thaana , Unified Canadian Aboriginal Syllabics ,
and Yi Syllables added, as well as a set of
ISO/IEC 10646-2:2001 41
Deseret , Gothic and Old Italic added, as well as sets of symbols
for Western music and
Byzantine music , and 42,711 additional CJK
Unified Ideographs .
ISO/IEC 10646-1:2000 plus Amendment 1
ISO/IEC 10646-2:2001 45
Philippine scripts Buhid , Hanunó\'o , Tagalog , and Tagbanwa
Cypriot syllabary , Limbu ,
Linear B , Osmanya , Shavian , Tai Le ,
and Ugaritic added, as well as Hexagram symbols .
ISO/IEC 10646:2003 plus Amendment 1
Buginese , Glagolitic , Kharoshthi , New Tai Lue , Old Persian ,
Syloti Nagri , and
Tifinagh added, and Coptic was disunified from
Greek . Ancient Greek numbers and musical symbols were also added.
ISO/IEC 10646:2003 plus Amendments 1 and 2, as well as four
characters from Amendment 3
Cuneiform , N\'Ko , Phags-pa , and Phoenician added.
ISO/IEC 10646:2003 plus Amendments 1, 2, 3 and 4
Carian , Cham , Kayah Li , Lepcha , Lycian , Lydian , Ol Chiki ,
Rejang , Saurashtra , Sundanese , and Vai added, as well as sets of
symbols for the
Phaistos Disc ,
Mahjong tiles , and Domino tiles .
There were also important additions for Burmese , additions of letters
and Scribal abbreviations used in medieval manuscripts , and the
Capital ẞ .
ISO/IEC 10646:2003 plus Amendments 1, 2, 3, 4, 5 and 6
Avestan , Bamum ,
Egyptian hieroglyphs (the Gardiner Set ,
comprising 1,071 characters),
Imperial Aramaic , Inscriptional Pahlavi
Inscriptional Parthian , Javanese ,
Kaithi , Lisu , Meetei Mayek ,
Old South Arabian , Old Turkic , Samaritan , Tai Tham and Tai Viet
added. 4,149 additional
CJK Unified Ideographs (CJK-C), as well as
extended Jamo for Old
Hangul , and characters for
Vedic Sanskrit .
ISO/IEC 10646:2010 plus the
Indian rupee sign
Batak , Brahmi , Mandaic , playing card symbols, transport and map
symbols, alchemical symbols , emoticons and emoji . 222 additional CJK
Unified Ideographs (CJK-D) added.
Chakma , Meroitic cursive , Meroitic hieroglyphs , Miao , Sharada ,
Sora Sompeng , and Takri .
ISO/IEC 10646:2012 plus the
Turkish lira sign
Turkish lira sign .
ISO/IEC 10646:2012 plus six characters
5 bidirectional formatting characters.
ISO/IEC 10646:2012 plus Amendments 1 and 2, as well as the Ruble
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 .
ISO/IEC 10646:2014 plus Amendment 1, as well as the Lari sign ,
CJK unified ideographs, and 41 emoji characters
Anatolian hieroglyphs , Hatran , Multani , Old Hungarian ,
SignWriting , 5,771
CJK unified ideographs , a set of lowercase
letters for Cherokee , and five emoji skin tone modifiers
ISO/IEC 10646:2014 plus Amendments 1 and 2, as well as Adlam, Newa,
Japanese TV symbols, and 74 emoji and symbols
Adlam , Bhaiksuki , Marchen , Newa , Osage , Tangut , and 72 emoji
ISO/IEC 10646:2017 plus 56 emoji characters, 285 hentaigana
characters, and 3 Zanabazar Square characters
Zanabazar Square , Soyombo , Masaram Gondi , Nushu , hentaigana
(non-standard hiragana ), 7,494
CJK unified ideographs , and 56 emoji
* ^ The number of characters listed for each version of
the total number of graphic, format and control characters (i.e.,
excluding private-use characters, noncharacters and surrogate code
Script (Unicode) Many modern applications can
render a substantial subset of the many scripts in
Unicode , as
demonstrated by this screenshot from the
Unicode covers almost all scripts (writing systems ) in current use
A total of 139 scripts 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.
Unicode Roadmap Committee (
Michael Everson , Rick McGowan, and
Ken Whistler) maintain the list of scripts that are candidates or
potential candidates for encoding and their tentative code block
assignments on the
Unicode Roadmap page of the
Unicode Consortium Web
site. For some scripts on the Roadmap, such as Jurchen and Khitan
small script , encoding proposals have been made and they are working
their way through the approval process. For others scripts, such as
Rongorongo , no proposal has yet been made, and they await
agreement on character repertoire and other details from the user
Some modern invented scripts which have not yet been included in
Tengwar ) or which do not qualify for inclusion in
Unicode due to lack of real-world use (e.g., Klingon ) are listed in
ConScript Unicode Registry , along with unofficial but widely used
Private Use Area code assignments.
There is also a Medieval
Font Initiative focused on special
Latin medieval characters. Part of these proposals have been already
included into Unicode.
The Script Encoding Initiative, a project run by Deborah Anderson at
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.
MAPPING AND ENCODINGS
Universal Character Set characters
Several mechanisms have been specified for implementing Unicode. The
choice depends on available storage space, source code compatibility,
and interoperability with other systems.
UNICODE TRANSFORMATION FORMAT AND UNIVERSAL CODED CHARACTER SET
Unicode defines two mapping methods: the _
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 values_. All UTF encodings map all code points (except
surrogates) to a unique sequence of bytes. The numbers in the names
of the encodings indicate the number of bits per code value (for UTF
encodings) or the number of bytes per code value (for UCS encodings).
UTF-16 are probably the most commonly used encodings. UCS-2
is an obsolete subset of UTF-16;
UTF-32 are functionally
UTF encodings include:
UTF-1 , a retired predecessor of UTF-8, maximizes compatibility
with ISO 2022 , no longer part of _The
UTF-7 , a 7-bit encoding sometimes used in e-mail, often
considered obsolete (not part of _The
Unicode Standard_, but only
documented as an informational RFC , i.e., not on the Internet
Standards Track either);
UTF-8 , an 8-bit variable-width encoding which maximizes
UTF-EBCDIC , an 8-bit variable-width encoding similar to UTF-8,
but designed for compatibility with
EBCDIC (not part of _The Unicode
UTF-16 , a 16-bit, variable-width encoding;
UTF-32 , a 32-bit, fixed-width encoding.
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 interchange of
Unicode text. It is used by
Linux distributions as a direct replacement for legacy
encodings in general text handling.
UTF-16 encodings specify the
Byte Order Mark
(BOM) for use at the beginnings of text files, which may be used for
byte ordering detection (or byte endianness detection). The BOM, code
point U+FEFF 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 other places, other than the beginning of text, conveys the
zero-width non-break space (a character with no appearance and no
effect other than preventing the formation of ligatures ).
The same character converted to
UTF-8 becomes the byte sequence EF BB
Unicode Standard allows that the BOM "can serve as signature
UTF-8 encoded text where the character set is unmarked". 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
UTF-8 from other character encodings without relying on
UTF-32 and UCS-4, one 32-bit code value serves as a fairly direct
representation of any character's code point (although the endianness,
which varies across different platforms, affects how the code value
manifests as an octet sequence). In the other encodings, each code
point may be represented by a variable number of code values. 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
Seed7 , use
UTF-32 as 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
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
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
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,
READY-MADE VERSUS COMPOSITE CHARACTERS
Unicode includes a mechanism for modifying character shape that
greatly extends the supported glyph repertoire. This covers the use of
combining diacritical marks . They are inserted after the main
character. Multiple combining diacritics may be stacked over the same
Unicode also contains precomposed versions of most
letter/diacritic combinations in normal use. These make 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 (LATIN SMALL LETTER E) followed by U+0301 (COMBINING ACUTE
ACCENT), but it can also be represented as the precomposed character
U+00E9 (LATIN SMALL LETTER E WITH ACUTE). Thus, in many cases, users
have multiple ways of encoding the same character. To deal with this,
Unicode provides the mechanism of canonical equivalence .
An example of this arises with
Hangul , the Korean alphabet. Unicode
provides a mechanism for composing
Hangul syllables with their
individual subcomponents, known as
Hangul Jamo . However, it also
provides 11,172 combinations of precomposed syllables made from the
most common jamo.
CJK ideographs currently have codes only for their precomposed
form. Still, most of those ideographs comprise simpler elements (often
called radicals in English), so in principle,
Unicode could have
decomposed them, as it did with Hangul. This would have greatly
reduced the number of required code points, while allowing the display
of virtually every conceivable ideograph (which might do away with
some of the problems caused by
Han unification ). A similar idea is
used by some input methods , such as Cangjie and Wubi . However,
attempts to do this for character encoding have stumbled over the fact
that ideographs do not decompose as simply or as regularly as Hangul
A set of radicals was provided in
Unicode 3.0 (
CJK radicals between
U+2E80 and U+2EFF, KangXi radicals in U+2F00 to U+2FDF, and
ideographic description characters from U+2FF0 to U+2FFB), but the
Unicode standard (ch. 12.2 of
Unicode 5.2) warns against using
ideographic description sequences as an alternate representation for
previously encoded characters:
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 .
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
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.
Several subsets of
Unicode are standardized:
Microsoft Windows since
Windows NT 4.0 supports
WGL-4 with 652 characters, which is considered
to support all contemporary European languages using the Latin, Greek,
Cyrillic script. Other standardized subsets of
Unicode include the
Multilingual European Subsets:
MES-1 (Latin scripts only, 335 characters), MES-2 (Latin, Greek and
Cyrillic 1062 characters) and MES-3A ">WGL-4, _MES-1_ and MES-2
Basic Latin (00–7F)
Latin-1 Supplement (80–FF)
_00–13,_ 14–15, _16–2B,_ 2C–2D, _2E–4D,_ 4E–4F,
Latin Extended-A (00–7F)
8F, 92, B7, DE-EF, FA–FF
Latin Extended-B (80–FF ...)
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)
74–75, 7A, 7E, 84–8A, 8C, 8E–A1, A3–CE, D7, DA–E1
00, 01–0C, 0D, 0E–4F, 50, 51–5C, 5D, 5E–5F, 90–91,
92–C4, C7–C8, CB–CC, D0–EB, EE–F5, F8–F9
02–03, 0A–0B, 1E–1F, 40–41, 56–57, 60–61, 6A–6B,
80–85, 9B, F2–F3
Latin Extended Additional (00–FF)
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)
13–14, _15,_ 17, _18–19,_ 1A–1B, _1C–1D,_ 1E, 20–22, 26,
30, 32–33, 39–3A, 3C, 3E
General Punctuation (00–6F)
44, 4A, 7F, 82
Superscripts and Subscripts (70–9F)
A3–A4, A7, _AC,_ AF
Currency Symbols (A0–CF)
05, 13, 16, _22, 26,_ 2E
Letterlike Symbols (00–4F)
Number Forms (50–8F)
_90–93,_ 94–95, A8
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)
02, 0A, 20–21, 29–2A
Miscellaneous Technical (00–FF)
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)
3A–3C, 40, 42, 60, 63, 65–66, _6A,_ 6B
Miscellaneous Symbols (00–FF)
Private Use Area (00–FF ...)
Alphabetic Presentation Forms (00–4F)
Rendering software which cannot process a
appropriately often displays it as an open rectangle, or the Unicode
"replacement character " (U+FFFD, �), to indicate the position of
the unrecognized character. Some systems have made attempts to provide
more information about such characters. The 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.
Unicode has become the dominant scheme for internal processing and
storage of text. Although a great deal of text is still stored in
Unicode is used almost exclusively for building new
information processing systems. Early adopters tended to use UCS-2
(the fixed-width two-byte precursor to UTF-16) and later moved to
UTF-16 (the variable-width 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,
Windows 2000 , Windows
Windows Vista and
Windows 7 ), which uses
UTF-16 as the sole
internal character encoding. The Java and .NET bytecode environments,
Mac OS X , and
KDE also use it for internal representation.
Windows 95 through
Microsoft Layer for
Unicode , as well
as on its descendants,
Windows 98 and
Windows ME .
UTF-8 (originally developed for Plan 9 ) 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
Unicode encoding used in
HTML documents on the
World Wide Web .
Multilingual text-rendering engines which use
ATSUI and Core Text
for Mac OS X, and
GTK+ and the
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 14755 , 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 in a screen, such as with a
character map program.
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
The adoption of
Unicode in email has been very slow. Some East Asian
text is still encoded in encodings such as
ISO-2022 , and some
devices, such as mobile phones, still cannot correctly handle Unicode
data. Support has been improving, however. Many major free mail
providers such as
Gmail ), and
) support it.
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. v 6 and older of
Internet Explorer did not render many code points unless
explicitly told to use a font that contains them.
Although syntax rules may affect the order in which characters are
allowed to appear,
XML (including X
HTML ) documents, by definition,
comprise characters from most of the
Unicode code points, with the
* most of the C0 control codes
* the permanently unassigned code points D800–DFFF
* FFFE or FFFF
HTML characters manifest either directly as bytes according to
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 , , , , , , , , and (or the
same numeric values expressed in hexadecimal, with 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
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
Mac OS X and also with
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.
PHILOSOPHICAL AND COMPLETENESS CRITICISMS
Han unification (the identification of forms in the East Asian
languages which one can treat as stylistic variations of the same
historical character) has become one of the most controversial aspects
of Unicode, despite the presence of a majority of experts from all
three regions in the
Ideographic Rapporteur Group (IRG), which advises
the Consortium and ISO on additions to the repertoire and on Han
Unicode has been criticized for failing to separately encode older
and alternative forms of kanji which, critics argue, complicates the
processing of ancient Japanese and uncommon Japanese names. This is
often due to the fact that
Unicode encodes characters rather than
glyphs (the visual representations of the basic character that often
vary from one language to another). Unification of glyphs leads to the
perception that the languages themselves, not just the basic character
representation, are being merged. There have been several attempts to
create alternative encodings that preserve the stylistic differences
between Chinese, Japanese, and Korean characters in opposition to
Unicode's policy of Han unification. An example of one is TRON
(although it is not widely adopted in Japan, there are some users who
need to handle historical Japanese text and favor it).
Although the repertoire of fewer than 21,000 Han characters in the
earliest version of
Unicode was largely limited to characters in
common modern usage,
Unicode now includes more than 70,000 Han
characters, and work is continuing to add thousands more historic and
dialectal characters used in China, Japan, Korea, Taiwan, and Vietnam.
Modern font technology provides a means to address the practical
issue of needing to depict a unified Han character in terms of a
collection of alternative glyph representations, in the form of
Unicode variation sequences . For example, the Advanced Typographic
OpenType permit one of a number of alternative glyph
representations to be selected when performing the character to glyph
mapping process. In this case, information can be provided within
plain text to designate which alternate character form to select.
Cyrillic characters shown with and without italics.
If the difference in the appropriate glyphs for two characters in the
same script differ only in the italic,
Unicode has generally unified
them, as can be seen in the comparison between Russian (labeled
standard) and Serbian characters at right, meaning that the
differences are displayed through smart font technology or manually
MAPPING TO LEGACY CHARACTER SETS
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 combining sequence of already
existing characters can no longer be added to the standard in order to
preserve interoperability between software using different versions of
Injective mappings must be provided between characters in existing
legacy character sets and characters in
Unicode to facilitate
Unicode and allow interoperability with legacy software.
Lack of consistency in various mappings between earlier Japanese
encodings such as
Unicode led to round-trip
format conversion mismatches, particularly the mapping of the
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).
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. (This encoding
also replaces tilde '~' 0x7E with macron '¯', now 0xAF.) The
separation of these characters exists in
ISO 8859-1 , from long before
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 (aka
conjuncts) out of components. Some local scholars argued in favor 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.
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
Tibetan script in 2003 when the Standardization Administration
of China proposed encoding 956 precomposed Tibetan syllables, but
these were rejected for encoding by the relevant ISO committee
ISO/IEC JTC 1/SC 2 ).
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. 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 "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 character See also:
Unicode 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.
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 , or AAT technologies for
advanced rendering features.
Unicode standard has imposed rules intended to guarantee
stability. Depending on the strictness of a rule, a change can be
prohibited or allowed. For example, a "name" given to a code point can
not 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 from
then on, an assigned name to a code point will never change anymore.
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, for example:
* U+2118 ℘ script capital p (
HTML · ): it is not a capital The
name says "capital", but it is a small letter. The true capital is
U+1D4AB 𝒫 MATHEMATICAL SCRIPT CAPITAL P (
* U+A015 ꀕ YI SYLLABLE WU (
HTML ): This is not a Yi syllable, but
a Yi iteration mark. Its name, however, cannot be changed due to the
policy of the Consortium.
* U+FE18 ︘ PRESENTATION FORM FOR VERTICAL RIGHT WHITE LENTICULAR
HTML ): _bracket_ is spelled wrong. Since this is the fixed
character name by policy, it cannot be changed.
Comparison of Unicode encodings
Cultural, political, and religious symbols in Unicode
International Components for Unicode (ICU), now as ICU-TC a part
List of binary codes
List of Unicode characters
* List of
HTML character entity references
Open-source Unicode typefaces
Standards related to Unicode
Universal Character Set
* Lotus Multi-
Byte Character Set (LMBCS), a parallel development
with similar intentions
* ^ "The
Unicode Standard: A Technical Introduction". Retrieved
* ^ _A_ _B_ _C_ _D_ _E_ Becker, Joseph D. (1998-09-10) . "Unicode
88" (PDF). _unicode.org_ (10th anniversary reprint ed.). 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 which
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 have been proved over the years in an
international line of communication multilingual system products. *
^ "Summary Narrative". Retrieved 2010-03-15.
* ^ History of
Unicode Release and Publication Dates on
_unicode.org._ Retrieved February 28, 2017.
* ^ Searle, Stephen J. "
Unicode Revisited". Retrieved 2013-01-18.
* ^ "Glossary of
Unicode Terms". Retrieved 2010-03-16.
* ^ "Appendix A: Notational Conventions" (PDF). _The Unicode
Unicode Consortium. June 2017.
* ^ _A_ _B_ "
Unicode Character Encoding Stability Policy".
* ^ "Properties" (PDF). Retrieved 2010-03-16.
* ^ "
Unicode Character Encoding Model". Retrieved 2010-03-16.
* ^ "
Unicode Named Sequences". Retrieved 2010-03-16.
* ^ "
Unicode Name Aliases". Retrieved 2010-03-16.
* ^ "The
Unicode Consortium Members". Retrieved 2010-03-16.
* ^ "
Unicode 6.1 Paperback Available".
_announcements_at_unicode.org_. Retrieved 2012-05-30.
* ^ "Enumerated Versions of The
Unicode Standard". Retrieved
* ^ "
Unicode Data 1.0.0". Retrieved 2010-03-16.
* ^ "
Unicode Data 1.0.1". Retrieved 2010-03-16.
* ^ "
Unicode Data 1995". Retrieved 2010-03-16.
* ^ "
Unicode Data-2.0.14". Retrieved 2010-03-16.
* ^ "
Unicode Data-2.1.2". Retrieved 2010-03-16.
* ^ "
Unicode Data-3.0.0". Retrieved 2010-03-16.
* ^ "
Unicode Data-3.1.0". Retrieved 2010-03-16.
* ^ "
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* ^ "
Unicode Data-4.0.0". Retrieved 2010-03-16.
* ^ "
Unicode Data". 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 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 Consortium. Retrieved 2015-06-17.
* ^ "
Unicode Data 8.0.0". Retrieved 2015-06-17.
* ^ "
Unicode Consortium. Retrieved 2016-06-21.
* ^ "
Unicode Data 9.0.0". Retrieved 2016-06-21.
* ^ Lobao, Martim (7 June 2016). "These Are The Two
Weren\'t Approved For
Unicode 9 But Which
Google Added To Android
Anyway". _Android Police_. Retrieved 4 September 2016.
* ^ "
Unicode Consortium. Retrieved 2017-06-20.
* ^ "
Unicode Data 10.0.0". Retrieved 2017-06-20.
* ^ "Character Code Charts". Retrieved 2010-03-17.
* ^ "About The Script Encoding Initiative". The
* ^ "UTF-8, UTF-16,
UTF-32 & BOM". _Unicode.org FAQ_. Retrieved 12
* ^ _The
Unicode Standard, Version 6.2_. The
2013. p. 561. ISBN 978-1-936213-08-5 .
* ^ CWA 13873:2000 – Multilingual European Subsets in ISO/IEC
10646-1 CEN Workshop Agreement 13873
* ^ Multilingual European Character Set 2 (MES-2) Rationale, Markus
Kuhn , 1998
* ^ Pike, Rob (2003-04-30). "
* ^ "ISO/IEC JTC1/SC 18/WG 9 N" (PDF). Retrieved 2012-06-04.
* ^ Wood, Alan. "Setting up Windows
Internet Explorer 5, 5.5 and 6
for Multilingual and
Unicode Support". Alan Wood. Retrieved
* ^ "Extensible Markup Language (XML) 1.1 (Second Edition)".
* ^ A Brief History of Character Codes, Steven J. Searle,
originally written 1999, last updated 2004
* ^ _A_ _B_ The secret life of Unicode: A peek at Unicode\'s soft
underbelly, Suzanne Topping, 1 May 2001 _(Internet Archive)_
* ^ AFII contribution about WAVE DASH,
character table for Japanese
* ^ _ISO 646-* Problem_, Section 18.104.22.168 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.
* ^ China (2 December 2002). "Proposal on Tibetan BrdaRten
Characters Encoding for
ISO/IEC 10646 in BMP" (PDF).
* ^ V. S. Umamaheswaran (7 November 2003). "Resolutions of WG 2
meeting 44" (PDF). Resolution M44.20.
Unicode stability policy
* ^ "
Unicode Technical Note #27: Known Anomalies in Unicode
Character Names". _unicode.org_. 10 April 2017.
Unicode chart: "actually this has the form of a lowercase
calligraphic p, despite its name"
* ^ "Misspelling of BRACKET in character name is a known defect"
Unicode Standard, Version 3.0_, The
Addison-Wesley Longman, Inc., April 2000. ISBN 0-201-61633-5
Unicode Standard, Version 4.0_, The
Addison-Wesley Professional, 27 August 2003. ISBN 0-321-18578-1
Unicode Standard, Version 5.0, Fifth Edition_, The Unicode
Consortium , Addison-Wesley Professional, 27 October 2006. ISBN
* Julie D. Allen. _The
Unicode Standard, Version 6.0_, The Unicode
Consortium , Mountain View, 2011, ISBN 9781936213016 , ().
* _The Complete Manual of Typography_, James Felici, Adobe Press;
1st edition, 2002. ISBN 0-321-12730-7
* _Unicode: A Primer_, Tony Graham, M 1st edition, 2002. ISBN
Unicode Explained_, Jukka K. Korpela, O'Reilly; 1st edition,
2006. ISBN 0-596-10121-X
Find more aboutUNICODEat's sister projects
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* Alan Wood\'s
Unicode Resources Contains lists of word processors