Whitespace character

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A whitespace character is a character data element that represents white space when text is rendered for display by a computer.

Contents

For example, a space character (U+0020 SPACE, ASCII 32) represents blank space such as a word divider in a Western script.

A printable character results in output when rendered, but a whitespace character does not. Instead, whitespace characters define the layout of text to a limited degree interrupting the normal sequence of rendering characters next to each other. The output of subsequent characters is typically shifted to the right (or to the left for right-to-left script) or to the start of the next line. The effect of multiple sequential whitespace characters is cumulative such that the next printable character is rendered in a location based on the accumulated effect of preceding whitespace characters.

The term whitespace is rooting in the common practice of rendering text on white paper. Normally, a whitespace character is not rendered as white. It affects rendering, but it is not itself rendered.

Overview

Width of various Unicode space characters Punctuation-Spaces.svg
Width of various Unicode space characters

A space character typically inserts horizontal space that is about as wide as a letter. For a monospaced font the width is the width of a letter, and for a variable-width font the width is font-specific. Some fonts support multiple space characters that have different widths.

A tab character typically inserts horizontal space that is based on tab stops which vary by application.

A newline character sequence typically moves the render output location to the beginning of the next line. If one follows text, it does not actually result in whitespace. But, two sequential newline sequences between text blocks results in a blank line between the blocks. The height of the blank line varies by application.

Using whitespace characters to layout text is a convention. Applications sometimes render whitespace characters as visible markup so that a user can see what is normally not visible.

Typically, a user types a space character by pressing spacebar, a tab character by pressing Tab ↹ and newline by pressing ↵ Enter.

Unicode

The table below lists the twenty-five characters defined as whitespace ("WSpace=Y", "WS") characters in the Unicode Character Database. [1] Seventeen use a definition of whitespace consistent with the algorithm for bidirectional writing ("Bidirectional Character Type=WS") and are known as "Bidi-WS" characters. The remaining characters may also be used, but are not of this "Bidi" type.

Note: Depending on the browser and fonts used to view the following table, not all spaces may be displayed properly.

Name Code point Width box May break?In
IDN?
Script Block General
category
Notes
character tabulationU+00099YesNoCommon Basic Latin Other,
control
HT, Horizontal Tab. HTML/XML named entity: 	, LaTeX: \tab, C escape: \t
line feedU+000A10Is a line-breakCommonBasic LatinOther,
control
LF, Line feed. HTML/XML named entity: 
, C escape: \n
line tabulationU+000B11Is a line-breakCommonBasic LatinOther,
control
VT, Vertical Tab. C escape: \v
form feedU+000C12Is a line-breakCommonBasic LatinOther,
control
FF, Form feed. C escape: \f
carriage returnU+000D13Is a line-breakCommonBasic LatinOther,
control
CR, Carriage return. C escape: \r
spaceU+002032YesNoCommonBasic LatinSeparator,
space
Most common (normal ASCII space). LaTeX: \ 
next lineU+0085133Is a line-breakCommon Latin-1
Supplement
Other,
control
NEL, Next line. LaTeX: \\
no-break spaceU+00A0160 NoNoCommonLatin-1
Supplement
Separator,
space
Non-breaking space: identical to U+0020, but not a point at which a line may be broken.
HTML/XML named entity:  ,  , LaTeX: ~
ogham space markU+16805760YesNoOghamOghamSeparator,
space
Used for interword separation in Ogham text. Normally a vertical line in vertical text or a horizontal line in horizontal text, but may also be a blank space in "stemless" fonts. Requires an Ogham font.
en quadU+20008192 YesNoCommon General
Punctuation
Separator,
space
Width of one en. U+2002 is canonically equivalent to this character; U+2002 is preferred.
em quadU+20018193YesNoCommonGeneral
Punctuation
Separator,
space
Also known as "mutton quad". Width of one em. U+2003 is canonically equivalent to this character; U+2003 is preferred.
en spaceU+20028194YesNoCommonGeneral
Punctuation
Separator,
space
Also known as "nut". Width of one en. U+2000 En Quad is canonically equivalent to this character; U+2002 is preferred.
HTML/XML named entity:  , LaTeX: \enspace (the LaTeX en space is a no-break space)
em spaceU+20038195YesNoCommonGeneral
Punctuation
Separator,
space
Also known as "mutton". Width of one em. U+2001 Em Quad is canonically equivalent to this character; U+2003 is preferred.
HTML/XML named entity:  , LaTeX: \quad
three-per-em spaceU+20048196YesNoCommonGeneral
Punctuation
Separator,
space
Also known as "thick space". One third of an em wide.
HTML/XML named entity:  , LaTeX: \; (the LaTeX thick space is a no-break space)
four-per-em spaceU+20058197YesNoCommonGeneral
Punctuation
Separator,
space
Also known as "mid space". One fourth of an em wide.
HTML/XML named entity:  
six-per-em spaceU+20068198YesNoCommonGeneral
Punctuation
Separator,
space
One sixth of an em wide. In computer typography, sometimes equated to U+2009.
figure spaceU+20078199NoNoCommonGeneral
Punctuation
Separator,
space
Figure space. In fonts with monospaced digits, equal to the width of one digit.
HTML/XML named entity:  
punctuation spaceU+20088200YesNoCommonGeneral
Punctuation
Separator,
space
As wide as the narrow punctuation in a font, i.e. the advance width of the period or comma. [2]
HTML/XML named entity:  
thin spaceU+20098201YesNoCommonGeneral
Punctuation
Separator,
space
Thin space; one-fifth (sometimes one-sixth) of an em wide. Recommended for use as a thousands separator for measures made with SI units. Unlike U+2002 to U+2008, its width may get adjusted in typesetting. [3]
HTML/XML named entity:  ,  , LaTeX: \, (the LaTeX thin space is a no-break space)
hair spaceU+200A8202YesNoCommonGeneral
Punctuation
Separator,
space
Thinner than a thin space. HTML/XML named entity:  ,  
line separatorU+20288232Is a line-breakCommonGeneral
Punctuation
Separator,
line
paragraph separatorU+20298233Is a line-breakCommonGeneral
Punctuation
Separator,
paragraph
narrow no-break spaceU+202F8239NoNoCommonGeneral
Punctuation
Separator,
space
Narrow no-break space. Similar in function to U+00A0 No-Break Space. When used with Mongolian, its width is usually one third of the normal space; in other context, its width sometimes resembles that of the Thin Space (U+2009). LaTeX: \,
medium mathematical spaceU+205F8287YesNoCommonGeneral
Punctuation
Separator,
space
MMSP. Used in mathematical formulae. Four-eighteenths of an em. [4] In mathematical typography, the widths of spaces are usually given in integral multiples of an eighteenth of an em, and 4/18 em may be used in several situations, for example between the a and the + and between the + and the b in the expression a + b. [5]
HTML/XML named entity:  , LaTeX: \: (the LaTeX medium space is a no-break space)
ideographic spaceU+300012288 YesNoCommon CJK Symbols
and
Punctuation
Separator,
space
As wide as a CJK character cell (fullwidth). Used, for example, in tai tou.
 Name  Code point Width box May break?In
IDN?
Script Block General
category
Notes
mongolian vowel separatorU+180E6158YesNoMongolian Mongolian Other,
Format
MVS. A narrow space character, used in Mongolian to cause the final two characters of a word to take on different shapes. [6] It is no longer classified as space character (i.e. in Zs category) in Unicode 6.3.0, even though it was in previous versions of the standard.
zero width space U+200B8203YesNo ?General
Punctuation
Other,
Format
ZWSP, zero-width space. Used to indicate word boundaries to text processing systems when using scripts that do not use explicit spacing. It is similar to the soft hyphen, with the difference that the latter is used to indicate syllable boundaries, and should display a visible hyphen when the line breaks at it.
HTML/XML named entity: ​ [7] [lower-alpha 3]
zero width non-joiner U+200C8204YesContext-dependent [12]  ?General
Punctuation
Other,
Format
ZWNJ, zero-width non-joiner. When placed between two characters that would otherwise be connected, a ZWNJ causes them to be printed in their final and initial forms, respectively.
HTML/XML named entity: ‌
zero width joiner U+200D8205YesContext-dependent [13]  ?General
Punctuation
Other,
Format
ZWJ, zero-width joiner. When placed between two characters that would otherwise not be connected, a ZWJ causes them to be printed in their connected forms. Can also be used to display joining forms in isolation. Depending on whether a ligature or conjunct is expected by default, can either induce (as in emoji and in Sinhala) or suppress (as in Devanagari) substitution with a single glyph, whilst still permitting use of individual joining forms (unlike ZWNJ).
HTML/XML named entity: ‍
word joiner U+20608288NoNo ?General
Punctuation
Other,
Format
WJ, word joiner. Similar to U+200B, but not a point at which a line may be broken.
HTML/XML named entity: ⁠
zero width non-breaking space U+FEFF65279NoNo ? Arabic
Presentation
Forms-B
Other,
Format
Zero-width non-breaking space. Used primarily as a Byte Order Mark. Use as an indication of non-breaking is deprecated as of Unicode 3.2; see U+2060 instead.
  1. White_Space is a binary Unicode property. [lower-alpha 4]
  2. "PropList-16.0.0.txt". Unicode. 2024-05-31. Retrieved 2024-09-13.
  3. Although ​ is one HTML5 named entity for U+200B, the additional names NegativeMediumSpace, NegativeThickSpace, NegativeThinSpace and NegativeVeryThinSpace (which are names used in the Wolfram Language for negative-advance spaces, which it maps to the Private Use Area) [8] [9] [10] [11] are also defined by HTML5 as aliases for U+200B (e.g. ​). [7]
  4. "Unicode Standard Annex #44, Unicode Character Database".

Substitute images

Unicode also provides some visible characters that can be used to represent various whitespace characters, in contexts where a visible symbol must be displayed:

Unicode space-illustrating characters (visible)
CodeDecimalName Block DisplayDescription
U+00B7183Middle dotLatin-1 Supplement · Interpunct
Named entity: ·
U+21A18609Downwards two headed arrowArrowsECMA-17 / ISO 2047 symbol for form feed (page break) [14]
U+22618810Identical toMathematical
Operators
Amongst other uses, is the ECMA-17 / ISO 2047 symbol for line feed [14]
U+237D9085Shouldered open boxMiscellaneous TechnicalUsed to indicate a NBSP
U+23CE9166Return symbolMiscellaneous TechnicalSymbol for a return key, which enters a line break
U+24099225Symbol for horizontal tabulationControl PicturesSubstitutes for a tab character
U+240A9226Symbol for line feedControl PicturesSubstitutes for a line feed
U+240B9227Symbol for vertical tabulationControl PicturesSubstitutes for a vertical tab (line tab)
U+240C9228Symbol for form feedControl PicturesSubstitutes for a form feed (page break)
U+240D9229Symbol for carriage returnControl PicturesSubstitutes for a carriage return
U+24209248Symbol for spaceControl PicturesSubstitutes for an ASCII space
U+24229250Blank symbolControl Picturesaka "substitute blank", [15] used in BCDIC, [15] EBCDIC, [15] ASCII-1963 [15] [16] etc. as a symbol for the word separator
U+24239251Open boxControl PicturesUsed in block letter handwriting at least since the 1980s when it is necessary to explicitly indicate the number of space characters (e.g. when programming with pen and paper). Used in a textbook (published 1982, 1984, 1985, 1988 by Springer-Verlag) on Modula-2, [17] a programming language where space codes require explicit indication. Also used in the keypad [n 1] of the Texas Instruments' TI-8x series of graphing calculators.
Named entity: ␣
U+24249252Symbol for newlineControl PicturesSubstitutes for a line break
U+25B39651White up-pointing triangleGeometric ShapesAmongst other uses, is the ECMA-17 / ISO 2047 symbol for the ASCII space [14]
U+2A5B10843Logical Or with middle stemSupplemental
Mathematical
Operators
Amongst other uses, is the ECMA-17 / ISO 2047 symbol for vertical tab (line tab) [14]
U+2AAA10922Smaller thanSupplemental
Mathematical
Operators
Amongst other uses, is the ECMA-17 / ISO 2047 symbol for carriage return [14]
U+2AAB10923Larger thanSupplemental
Mathematical
Operators
Amongst other uses, is the ECMA-17 / ISO 2047 symbol for the tab character [14]
U+303712343Ideographic Telegraph Line Feed
Separator Symbol
CJK Symbols
and Punctuation
Graphic used for code 9999 in Chinese telegraph code, representing a line feed
  1. Above the zero "0" or negative "(‒)" key.
Exact space
  • The Cambridge Z88 provided a special "exact space" (code point 160 aka 0xA0) (invokable by key shortcut +SPACE [18] ), displayed as "…" by the operating system's display driver. [19] [20] It was therefore also known as "dot space" in conjunction with BBC BASIC. [19] [20]
  • Under code point 224 (0xE0) the computer also provided a special three-character-cells-wide SPACE symbol "SPC" (analogous to Unicode's single-cell-wide U+2420). [19] [20]

Non-space blanks

  • The Braille Patterns Unicode block contains U+2800BRAILLE PATTERN BLANK, a Braille pattern with no dots raised. Some fonts display the character as a fixed-width blank, however the Unicode standard explicitly states that it does not act as a space. [21]
  • Unicode's coverage of the Korean alphabet includes several code points which represent the absence of a written letter, and thus do not display a glyph:
    • Unicode includes a Hangul Filler character in the Hangul Compatibility Jamo block (U+3164HANGUL FILLER). This is classified as a letter, but displayed as an empty space, like a Hangul block containing no jamo. It is used in KS X 1001 Hangul combining sequences to introduce them or denote the absence of a letter in a position, but not in Unicode's combining jamo system. [22]
    • Unicode's combining jamo system uses similar Hangul Choseong Filler and Hangul Jungseong Filler characters to denote the absence of a letter in initial or medial position within a syllable block, which are included in the Hangul Jamo block (U+115FHANGUL CHOSEONG FILLER, U+1160HANGUL JUNGSEONG FILLER). [23]
    • Additionally, a Halfwidth Hangul Filler is included in the Halfwidth and Fullwidth Forms (U+FFA0HALFWIDTH HANGUL FILLER), which is used when mapping from encodings which include characters from both Johab (or Wansung) and N-byte Hangul (or its EBCDIC counterpart), such as IBM-933, which includes both Johab and EBCDIC fillers. [24] [25]

Whitespace and digital typography

The Chicago Manual of Style has rules for using the different sized whitespaces. Traditional spacing examples from the 1911 Chicago Manual of Style.png
The Chicago Manual of Style has rules for using the different sized whitespaces.

On-screen display

Text editors, word processors, and desktop publishing software differ in how they represent whitespace on the screen, and how they represent spaces at the ends of lines longer than the screen or column width. In some cases, spaces are shown simply as blank space; in other cases they may be represented by an interpunct or other symbols. Many different characters (described below) could be used to produce spaces, and non-character functions (such as margins and tab settings) can also affect whitespace.

Many of the Unicode space characters were created for compatibility with classic print typography. [26]

Even if digital typography has algorithmic kerning and justification, those space characters can be used to supplement the electronic formatting when needed.

Variable-width general-purpose space

In computer character encodings, there is a normal general-purpose space (Unicode character U+0020) whose width will vary according to the design of the typeface. Typical values range from 1/5 em to 1/3 em (in digital typography an em is equal to the nominal size of the font, so for a 10-point font the space will probably be between 2 and 3.3 points). Sophisticated fonts may have differently sized spaces for bold, italic, and small-caps faces, and often compositors will manually adjust the width of the space depending on the size and prominence of the text.

In addition to this general-purpose space, it is possible to encode a space of a specific width. See the table below for a complete list.

Hair spaces around dashes

Em dashes used as parenthetical dividers, and en dashes when used as word joiners, are usually set continuous with the text. [27] However, such a dash can optionally be surrounded with a hair space, U+200A, or thin space , U+2009. The hair space can be written in HTML by using the numeric character references   or  , or the named entity  , although that is not universally supported in browsers as of 2016.[ needs update ] The thin space is named entity   and numeric references   or  . These spaces are much thinner than a normal space (except in a monospaced (non-proportional) font), with the hair space in particular being the thinnest of horizontal whitespace characters.

Normal space versus hair and thin spaces (as rendered by your browser)
Normal space with em dashleft  right
Thin space with em dashleftright
Hair space with em dashleft  right
No space with em dashleftright

Computing applications

Programming languages

In most programming language syntax, whitespace characters can be used to separate tokens. For a free-form language, whitespace characters are ignored by code processors (i.e. compiler). Even when language syntax requires white space, often multiple whitespace characters are treated the same as a single. In an off-side rule language, indentation white space is syntactically significant. In the satirical and contrarian language called Whitespace, whitespace characters are the only significant characters and normal text is ignored.

Good use of white space in source code can group related logic and make the code easier to understand. Excessive use of whitespace, including at the end of a line where it provides no rendering behavior, is considered a nuisance.

Most languages only recognize whitespace characters that have an ASCII code. They disallow most or all of the Unicode codes listed above. The C language defines whitespace characters to be "space, horizontal tab, new-line, vertical tab, and form-feed". [28] The HTTP network protocol requires different types of whitespace to be used in different parts of the protocol, such as: only the space character in the status line, CRLF at the end of a line, and "linear whitespace" in header values. [29]

Command-line parsing

Typical command-line parsers use the space character to delimit arguments. A value with an embedded space character is problematic since it causes the value to parse as multiple arguments. Typically, a parser allows for escaping the normal argument parsing by enclosing the text in quotes.

Consider that one wants to list the files in directory named "foo bar". This command instead lists the files matching either "foo" or "bar":

lsfoobar 

This command correctly specifies a single argument:

ls"foo bar"

Markup languages

Some markup languages, such as SGML, preserve whitespace as written.

Web markup languages such as XML and HTML treat whitespace characters specially, including space characters, for programmers' convenience. One or more space characters read by conforming display-time processors of those markup languages are collapsed to 0 or 1 space, depending on their semantic context. For example, double (or more) spaces within text are collapsed to a single space, and spaces which appear on either side of the "=" that separates an attribute name from its value have no effect on the interpretation of the document. Element end tags can contain trailing spaces, and empty-element tags in XML can contain spaces before the "/>". In these languages, unnecessary whitespace increases the file size, and so may slow network transfers. On the other hand, unnecessary whitespace can also inconspicuously mark code, similar to, but less obvious than comments in code. This can be desirable to prove an infringement of license or copyright that was committed by copying and pasting.

In XML attribute values, sequences of whitespace characters are treated as a single space when the document is read by a parser. [30] Whitespace in XML element content is not changed in this way by the parser, but an application receiving information from the parser may choose to apply similar rules to element content. An XML document author can use the xml:space="preserve" attribute on an element to instruct the parser to discourage the downstream application from altering whitespace in that element's content.

In most HTML elements, a sequence of whitespace characters is treated as a single inter-word separator, which may manifest as a single space character when rendering text in a language that normally inserts such space between words. [31] Conforming HTML renderers are required to apply a more literal treatment of whitespace within a few prescribed elements, such as the pre tag and any element for which CSS has been used to apply pre-like whitespace processing. In such elements, space characters will not be "collapsed" into inter-word separators.

In both XML and HTML, the non-breaking space character, along with other non-"standard" spaces, is not treated as collapsible "whitespace", so it is not subject to the rules above.

File names

Such usage is similar to multiword file names written for operating systems and applications that are confused by embedded space codessuch file names instead use an underscore (_) as a word separator, as_in_this_phrase.

Another such symbol was U+2422BLANK SYMBOL. This was used in the early years of computer programming when writing on coding forms. Keypunch operators immediately recognized the symbol as an "explicit space". [15] It was used in BCDIC, [15] EBCDIC, [15] and ASCII-1963. [15]

See also

Related Research Articles

While Hypertext Markup Language (HTML) has been in use since 1991, HTML 4.0 from December 1997 was the first standardized version where international characters were given reasonably complete treatment. When an HTML document includes special characters outside the range of seven-bit ASCII, two goals are worth considering: the information's integrity, and universal browser display.

<span class="mw-page-title-main">Plain text</span> Term for computer data consisting only of unformatted characters of readable material

In computing, plain text is a loose term for data that represent only characters of readable material but not its graphical representation nor other objects. It may also include a limited number of "whitespace" characters that affect simple arrangement of text, such as spaces, line breaks, or tabulation characters. Plain text is different from formatted text, where style information is included; from structured text, where structural parts of the document such as paragraphs, sections, and the like are identified; and from binary files in which some portions must be interpreted as binary objects.

<span class="mw-page-title-main">Unicode</span> Character encoding standard

Unicode, formally The Unicode Standard, is a text encoding standard maintained by the Unicode Consortium designed to support the use of text in all of the world's writing systems that can be digitized. Version 16.0 of the standard defines 154998 characters and 168 scripts used in various ordinary, literary, academic, and technical contexts.

<span class="mw-page-title-main">XML</span> Markup language by the W3C for encoding of data

Extensible Markup Language (XML) is a markup language and file format for storing, transmitting, and reconstructing arbitrary data. It defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. The World Wide Web Consortium's XML 1.0 Specification of 1998 and several other related specifications—all of them free open standards—define XML.

An interpunct·, also known as an interpoint, middle dot, middot, centered dot or centred dot, is a punctuation mark consisting of a vertically centered dot used for interword separation in Classical Latin. It appears in a variety of uses in some modern languages.

In word processing and digital typesetting, a non-breaking space, also called NBSP, required space, hard space, or fixed space, is a space character that prevents an automatic line break at its position. In some formats, including HTML, it also prevents consecutive whitespace characters from collapsing into a single space. Non-breaking space characters with other widths also exist.

ISO 15924, Codes for the representation of names of scripts, is an international standard defining codes for writing systems or scripts. Each script is given both a four-letter code and a numeric code.

<span class="mw-page-title-main">Korean language and computers</span> Input and use of Korean on computers

The writing system of the Korean language is a syllabic alphabet of character parts organized into character blocks representing syllables. The character parts cannot be written from left to right on the computer, as in many Western languages. Every possible syllable in Korean would have to be rendered as syllable blocks by a font, or each character part would have to be encoded separately. Unicode has both options; the character parts ㅎ (h) and ㅏ (a), and the combined syllable 하 (ha), are encoded.

.properties is a file extension for files mainly used in Java-related technologies to store the configurable parameters of an application. They can also be used for storing strings for Internationalization and localization; these are known as Property Resource Bundles.

Symbol is one of the four standard fonts available on all PostScript-based printers, starting with Apple's original LaserWriter (1985). It contains a complete unaccented Greek alphabet and a selection of commonly used mathematical symbols. Insofar as it fits into any standard classification, it is a serif font designed in the style of Times New Roman.

Unicode equivalence is the specification by the Unicode character encoding standard that some sequences of code points represent essentially the same character. This feature was introduced in the standard to allow compatibility with preexisting standard character sets, which often included similar or identical characters.

<span class="mw-page-title-main">Universal Character Set characters</span> Complete list of the characters available on most computers

The Unicode Consortium and the ISO/IEC JTC 1/SC 2/WG 2 jointly collaborate on the list of the characters in the Universal Coded Character Set. The Universal Coded Character Set, most commonly called the Universal Character Set, is an international standard to map characters, discrete symbols used in natural language, mathematics, music, and other domains, to unique machine-readable data values. By creating this mapping, the UCS enables computer software vendors to interoperate, and transmit—interchange—UCS-encoded text strings from one to another. Because it is a universal map, it can be used to represent multiple languages at the same time. This avoids the confusion of using multiple legacy character encodings, which can result in the same sequence of codes having multiple interpretations depending on the character encoding in use, resulting in mojibake if the wrong one is chosen.

Specials is a short Unicode block of characters allocated at the very end of the Basic Multilingual Plane, at U+FFF0–FFFF. Of these 16 code points, five have been assigned since Unicode 3.0:

<span class="mw-page-title-main">Halfwidth and fullwidth forms</span> Alternative width characters in East Asian typography

In CJK computing, graphic characters are traditionally classed into fullwidth and halfwidth characters. Unlike monospaced fonts, a halfwidth character occupies half the width of a fullwidth character, hence the name.

KS X 1001, "Code for Information Interchange ", formerly called KS C 5601, is a South Korean coded character set standard to represent Hangul and Hanja characters on a computer.

The Unicode Standard assigns various properties to each Unicode character and code point.

In typography, a quad was a metal spacer used in letterpress typesetting. The term was later adopted as the generic name for two common sizes of spaces in typography, regardless of the form of typesetting used. An em quad is a space that is one em wide; as wide as the height of the font. An en quad is a space that is one en wide: half the width of an em quad.

Tamil All Character Encoding (TACE16) is a scheme for encoding the Tamil script in the Private Use Area of Unicode, implementing a syllabary-based character model differing from the modified-ISCII model used by Unicode's existing Tamil implementation.

References

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  4. "General Punctuation" (PDF). The Unicode Standard 5.1. Unicode Inc. 1991–2008. Retrieved 2009-05-13.
  5. Sargent, Murray III (2006-08-29). "Unicode Nearly Plain Text Encoding of Mathematics (Version 2)". Unicode Technical Note #28. Unicode Inc. pp. 19–20. Retrieved 2009-05-19.
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  7. 1 2 Hickson, Ian. "12.5 Named character references". HTML Standard. WHATWG.
  8. Wolfram. "\[NegativeThickSpace]". Wolfram Language Documentation.
  9. Wolfram. "\[NegativeMediumSpace]". Wolfram Language Documentation.
  10. Wolfram. "\[NegativeThinSpace]". Wolfram Language Documentation.
  11. Wolfram. "\[NegativeVeryThinSpace]". Wolfram Language Documentation.
  12. Faltstrom, P., ed. (August 2010). "Zero Width Non-Joiner". The Unicode Code Points and Internationalized Domain Names for Applications (IDNA). IETF. sec. A.1. doi: 10.17487/RFC5892 . RFC 5892 . Retrieved September 4, 2019.
  13. Faltstrom, P., ed. (August 2010). "Zero Width Joiner". The Unicode Code Points and Internationalized Domain Names for Applications (IDNA). IETF. sec. A.2. doi: 10.17487/RFC5892 . RFC 5892 . Retrieved September 4, 2019.
  14. 1 2 3 4 5 6 European Computer Manufacturers Association (1968-11-28). Graphic Representation of the Control Characters of the ECMA 7-Bit Coded Character Set for Information Interchange (PDF). ECMA-17.
  15. 1 2 3 4 5 6 7 8 Mackenzie, Charles E. (1980). Coded Character Sets, History and Development (PDF). The Systems Programming Series (1 ed.). Addison-Wesley Publishing Company, Inc. pp. 41, 47, 52, 102–103, 117, 119, 130, 132, 141, 148, 150–151, 212, 424. ISBN   978-0-201-14460-4. LCCN   77-90165. Archived (PDF) from the original on May 26, 2016. Retrieved August 25, 2019.
  16. "American Standard Code for Information Interchange, ASA X3.4-1963". American Standards Association (ASA). 1963-06-17.
  17. Wirth, Niklaus (1988). Programming in Modula-2 (PDF). doi:10.1007/978-3-642-83565-0. ISBN   978-3-642-83567-4.
  18. "Cambridge Z88 User Guide". 4.7 (4th ed.). Cambridge Computer Limited. 2016 [1987]. Basic concepts - The keyboard. Archived from the original on 2016-12-12. Retrieved 2016-12-12.
  19. 1 2 3 "Cambridge Z88 User Guide". 4.0 (4th ed.). Cambridge Computer Limited. 1987. Appendix D. Archived from the original on 2016-12-12. Retrieved 2016-12-12.
  20. 1 2 3 "Cambridge Z88 User Guide". 4.7 (4th ed.). Cambridge Computer Limited. 2015 [1987]. Appendix D. Archived from the original on 2016-12-12. Retrieved 2016-12-12.
  21. Unicode chart U+2800, braille patterns
  22. Chung, Jaemin (2017-03-30). Proposal to add an informative note to U+3164 HANGUL FILLER (PDF). Unicode Consortium. UTC L2/17-081.
  23. Hangul Jamo (PDF). Unicode Consortium. 2020-10-25.
  24. "ibm-933_P110-1995". ICU Demonstration - Converter Explorer. International Components for Unicode.
  25. "ibm-933_P110-1995 (lead bytes 0E84)". ICU Demonstration - Converter Explorer. International Components for Unicode.
  26. "Chapter 6 — Writing Systems and Punctuation" (PDF). The Unicode Standard 15.0, electronic edition. Unicode Consortium. 2022-09-13. pp. 12–13 (267–268). Retrieved 2022-12-23. The fixed-width space characters (U+2000..U+200A) are derived from conventional (hot lead) typography. Algorithmic kerning and justification in computerized typography do not use these characters. However, where they are used (for example, in typesetting mathematical formulae), their width is generally font-specified, and they typically do not expand during justification. The exception is U+2009 thin space, which sometimes gets adjusted.
  27. Usage of the different dash types is illustrated, e.g., in The Chicago Manual of Style , §§ 6.80, 6.83–6.86
  28. http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1548.pdf Section 6.4, paragraph 3
  29. Fielding, R.; et al. (June 1999), "2.2 Basic Rules", Hypertext Transfer Protocol—HTTP/1.1, doi:10.17487/RFC2616, RFC   2616
  30. "3.3.3 Attribute-Value Normalization". Extensible Markup Language (XML) 1.0 (Fifth Edition). World Wide Web Consortium.
  31. "9.1 Whitespace". W3CHTML 4.01 Specification. World Wide Web Consortium.