Space (punctuation)

From Wikipedia, the free encyclopedia
  (Redirected from Hair space)
Jump to: navigation, search
apostrophe   '
brackets [ ]  ( )  { }  ⟨ ⟩
colon :
comma ,  ،  
dash   –  —  ―
ellipsis   ...  . . .
exclamation mark !
full stop, period .
hyphen-minus -
question mark ?
quotation marks ‘ ’  “ ”  ' '  " "
semicolon ;
slash, stroke, solidus /  
Word dividers
interpunct ·
General typography
ampersand &
asterisk *
at sign @
backslash \
caret ^
dagger † ‡
degree °
ditto mark
inverted exclamation mark ¡
inverted question mark ¿
number sign, pound, hash, octothorpe #
numero sign
obelus ÷
ordinal indicator º ª
percent, per mil % ‰
plus and minus + −
basis point
section sign §
tilde ~
underscore, understrike _
vertical bar, pipe, broken bar |    ¦
Intellectual property
copyright ©
sound-recording copyright
registered trademark ®
service mark
Uncommon typography
index, fist
irony punctuation
reference mark
In other scripts

In writing, a space ( ) is a blank area devoid of content, serving to separate words, letters, numbers, and punctuation. Conventions for interword and intersentence spaces vary among languages, and in some cases the spacing rules are quite complex. In the classical period, Latin was written with interpuncts (centred dots) as word separators, but that practice was abandoned sometime around AD 200 in favour of scriptio continua, i.e., with the words running together without any word separators. In around AD 600–800, blank spaces started being inserted between words in Latin, and that practice carried over to all languages using the Latin alphabet (e.g., English).

In typesetting, spaces have historically been of multiple lengths with particular space-lengths being used for specific typographic purposes, such as separating words or separating sentences or separating punctuation from words. Following the invention of the typewriter and the subsequent overlap of designer style-preferences and computer-technology limitations, much of this reader-centric variation was lost in normal use.

In computer representation of text, spaces of various sizes, styles, or language characteristics (different space characters) are indicated with unique code points.

Use of the space in natural languages[edit]

Spaces between words[edit]

Main article: Word divider

Modern English uses a space to separate words, but not all languages follow this practice. Spaces were not used to separate words in Latin until roughly AD 600–800. Ancient Hebrew and Arabic did use spaces, partly to compensate in clarity for the lack of vowels.[citation needed] Traditionally, all CJK languages have no spaces: modern Chinese and Japanese (except when written with little or no kanji) still do not, but modern Korean uses spaces.

Runic texts use either an interpunct-like or a colon-like punctuation mark to separate words. There are two Unicode characters dedicated for this: U+16EB runic single punctuation and U+16EC runic multiple punctuation.

Spaces between sentences[edit]

Main article: Sentence spacing

Languages with a Latin-derived alphabet have used various methods of sentence spacing since the advent of movable type in the 15th century.

  • One space (French Spacing). This is a common convention in most countries that use the ISO basic Latin alphabet for published and final written work, as well as digital (World Wide Web) media.[1] Web browsers usually do not differentiate between single and multiple spaces in source code when displaying text, unless text is given a "white-space" CSS attribute. Without this being set, collapsing strings of spaces to a single space allows HTML source code to be spaced in a more readable way, at the expense of control over spacing of the rendered page.[2]
  • Double space (English Spacing). It is sometimes claimed that this convention stems from the use of the monospaced font on typewriters.[3] However, instructions to use more spacing between sentences than words date back centuries, and two spaces on a typewriter was the closest approximation to typesetters' previous rules aimed at improving readability.[4] Wider spacing continued to be used by both typesetters and typists until the Second World War, after which typesetters gradually transitioned to word spacing between sentences in published print, while typists continued the practice of using two spaces.[5][6][7][8][9][10][11][12][13][14][15]
  • One widened space, typically one-and-a-third to slightly less than twice as wide as a word space. This spacing was sometimes used in typesetting before the 19th century. It has also been used in other non-typewriter typesetting systems such as the Linotype machine[16] and the TeX system.[17] Modern computer-based digital fonts can adjust the spacing after terminal punctuation as well, creating a space slightly wider than a standard word space.[18]
  • No space. According to Lynne Truss, "young people" today using digital media "are now accustomed to following a full stop with a lower-case letter and no space".[19]

There has been some controversy regarding the proper amount of sentence spacing in typeset material. The Elements of Typographic Style states that only a single word space is required for sentence spacing since "Larger spaces...are themselves punctuation."[20] [clarification needed]

Spaces and unit symbols[edit]

The International System of Units, or SI,[21] and the style guide of the English-language Wikipedia[22] recommend a (non-breaking) space between a number and its units, as well as between units in the case of compound units, but never between a prefix and the basic unit.

5.0 cm not 5.0 c m
45 kg not 45kg or 45 k g
32 °C not 32°C or 32° C
20 kN m not 20 kNm or 20 k Nm
50 % not 50% (Note:  % is not an SI unit, and Wikipedia does not follow this SI recommendation.)

The only exceptions to this rule in the SI are for the symbols for degree, minute, and second for plane angle, as in 30° 22′ 8″.

Some sources[citation needed] say that a hyphen may be inserted between a numeral and a symbol used adjectivally, for the sake of clarity:

35-mm film
60-W bulb

However, some other style guides, including Wikipedia's, deprecate hyphenation in these cases. The SI allows a hyphen between the numeral and the unit only when the name of the unit is spelled out, as 35-millimetre film.[21]

Space characters and digital typography[edit]

Variable-width general-purpose space[edit]

In computer character encodings, there is a normal general-purpose space (Unicode character U+0020; 32 decimal) 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.

Breaking and non-breaking spaces[edit]

By default, computer programs usually assume that, in flowing text, a line break may as necessary be inserted at the position of a space. The non-breaking space, U+00A0 (160 decimal), named entity   is intended to render the same as a normal space but prevents line-wrapping at that position.

Hair spaces around dashes[edit]

In American typography, both en dashes and em dashes are set continuous with the text (as illustrated by use in The Chicago Manual of Style, 6.80, 6.83–86). However, an em dash can optionally be surrounded with a so-called hair space, U+200A (8202 decimal), or thin space, U+2009 (8201 decimal). The thin space can be written in HTML by using the named entity   and the hair space can be written using numeric character reference   or  . This space should be much thinner than a normal space, and is seldom used on its own.

Normal space versus hair space
(as rendered by your browser)
Normal space left right
Normal space with em dash left — right
Thin space with em dash left — right
Hair space with em dash left — right
No space with em dash left—right

Spaces in Unicode[edit]

Relative widths of various spaces in Unicode.

Unicode defines[23] several space characters with specific semantics and rendering characteristics, as shown in the table below. Depending on the browser and fonts used to view this table, not all spaces may display properly:

Spacing characters in Unicode
Code Dec Break in IDN HTML Name Block Display
U+0020 32 Yes No Space Basic Latin ] [
Normal space, same as ASCII character 0x20
U+00A0 160 No No   Non-Breaking Space Latin-1 Supplement ] [
Identical to U+0020, but not a point at which a line may be broken
U+1680 5760 Yes Yes Ogham Space Mark Ogham ] [
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.
U+180E 6158 Yes Yes Mongolian Vowel Separator (MVS) Mongolian ]᠎[
A narrow space character (not to be confused with "thin space", below) used in Mongolian to cause the final two characters of a word to take on different shapes.[24] 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.
U+2000 8192 Yes No[a] En quad General Punctuation ] [
Width of one en. U+2002 is canonically equivalent to this character; U+2002 is preferred.
U+2001 8193 Yes No[a] Em quad
Mutton quad
General Punctuation ] [
Width of one em. U+2003 is canonically equivalent to this character; U+2003 is preferred.
U+2002 8194 Yes No[a]   En Space
General Punctuation ] [
Width of one en. U+2000 En Quad is canonically equivalent to this character; U+2002 is preferred.
U+2003 8195 Yes No[a]   Em Space
General Punctuation ] [
Width of one em. U+2001 Em Quad is canonically equivalent to this character; U+2003 is preferred.
U+2004 8196 Yes No[a] Three-Per-Em Space
Thick Space
General Punctuation ] [
One third of an em wide
U+2005 8197 Yes No[a] Four-Per-Em Space
Mid Space
General Punctuation ] [
One fourth of an em wide
U+2006 8198 Yes No[a] Six-Per-Em Space General Punctuation ] [
One sixth of an em wide. In computer typography sometimes equated to U+2009.
U+2007 8199 No No[a] Figure Space General Punctuation ] [
In fonts with monospaced digits, equal to the width of one digit.
U+2008 8200 Yes No[a] Punctuation Space General Punctuation ] [
As wide as the narrow punctuation in a font, i.e. the advance width of the period or comma.[25]
U+2009 8201 Yes No[a]   Thin Space General Punctuation ] [
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.[26]
U+200A 8202 Yes No[a] Hair Space General Punctuation ] [
Thinner than a thin space
U+200B 8203 Yes No[a] Zero Width Space (ZWSP) General Punctuation ]​[
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.
U+200C 8204 Yes Yes ‌ Zero Width Non Joiner (ZWNJ) General Punctuation ]‌[
When placed between two characters that would otherwise be connected, a ZWNJ causes them to be printed in their final and initial forms, respectively.
U+200D 8205 Yes Yes ‍ Zero Width Joiner (ZWJ) General Punctuation ]‍[
When placed between two characters that would otherwise not be connected, a ZWJ causes them to be printed in their connected forms.
U+202F 8239 No No[a] Narrow No-Break Space General Punctuation ] [
Similar in function to U+00A0 No-Break Space. Introduced in Unicode 3.0 for Mongolian,[27] to separate a suffix from the word stem without indicating a word boundary. When used with Mongolian, its width is usually one third of the normal space; in other context, its width resembles that of the Thin Space (U+2009) at least with some fonts. This character is also used in French before ":;?!»" and after "«"[original research?].
U+205F 8287 Yes No[a] Medium Mathematical Space (MMSP) General Punctuation ] [
Used in mathematical formulae. Four-eighteenths of an em.[28] 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.[29]
U+2060 8288 No Yes Word Joiner (WJ) General Punctuation ]⁠[
Identical to U+200B, but not a point at which a line may be broken. Introduced in Unicode 3.2 to replace the deprecated "zero width no-break space" function of the U+FEFF character.
U+3000 12288 Yes No[a] Ideographic Space (used for example as tai tou) CJK Symbols and Punctuation ] [
As wide as a CJK character cell (fullwidth)
U+FEFF 65279 No Yes Zero Width No-Break Space
= Byte Order Mark (BOM)
Arabic Presentation Forms-B ][
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. ^ a b c d e f g h i j k l m n o This character is blacklisted for domain names by browsers because it might be used for phishing.[30]

Unicode also provides some visible characters to stand in for space when necessary:

Space illustrating characters (visible) in Unicode
Code Dec Name Block Display Description
U+00B7 183 Middle dot Basic Latin · interpunct, used in text processors. HTML also: ·
U+237D 9085 Shouldered open box Miscellaneous Technical used for NBSP
U+2420 9248 Symbol for space Control Pictures
U+2422 9250 Blank symbol Control Pictures
U+2423 9251 Open box Control Pictures

Non-space blanks:

  • The Braille Patterns Unicode block contains U+2800 braille pattern blank (HTML: ⠀), 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.

Use of the space in computing[edit]

In programming language syntax, spaces are frequently used to explicitly separate tokens. Aside from this use, spaces and other whitespace characters are usually ignored by modern programming languages. Exceptions are Haskell, occam, ABC, and Python, which use the amount of whitespace in indentation to indicate the bounds of a block, and a whimsical language called Whitespace, where whitespace is the only meaningful syntactical element.

In commands processed by command processors, e.g., in scripts and typed in, the space character can cause problems as it has two possible functions: as part of a command or parameter, or as a parameter or name separator. Ambiguity can be prevented either by prohibiting embedded spaces, or by enclosing a name with embedded spaces between quote characters.

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.

Hard spaces (contrasted with "soft spaces") may be defined by some word processors and operating systems as either a non-breaking space, a non-combining/non-expanding space, or some other special character.

Space characters in markup languages[edit]

Generalised markup languages, such as SGML, do not treat space characters differently from other characters.

However, special-purpose markup languages may. In particular, 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 XML attribute values, sequences of whitespace characters are treated as a single space when the document is read by a parser.[32] 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.[33] 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.

See also[edit]


  1. ^ Einsohn, Amy (2006). "Punctuation, Eyeballing every mark". The Copyeditor's Handbook: A Guide for Book Publishing and Corporate Communications (2nd ed.). Berkeley, Los Angeles, London: University of California Press. p. 113. ISBN 9780520246881. Retrieved 2010-04-25. "If you are working on documents that will be printed without any intervention from a compositor (e.g., documents produced on the office laser printer), you will have to carefully scrutinize every piece of punctuation to be sure that the document contains the correct character (see table 5). You should also delete any extra wordspacing before and after punctuation marks. The conventions are: One space follows sentence-ending punctuation mark (period, question mark, or exclamation point). One space follows comma, colon, or semicolon ..." 
  2. ^ Thomas A. Fine. "How many spaces at the end of a sentence? One or two?". 
  3. ^ Farhad Manjoo (2011-01-13). "Space Invaders: Why you should never, ever use two spaces after a period.". Slate. Retrieved 2011-03-29. 
  4. ^ Heraclitus (1 November 2011). "Why two spaces after a period isn't wrong". 
  5. ^ Felici, James (2003). The Complete Manual of Typography: A Guide to Setting Perfect Type. Berkeley, CA: Peachpit Press. p. 80. ISBN 0321127307. ;
  6. ^ David Spencer (24 May 2011). "The Curious Misconception Surrounding Sentence Spacing". Type Desk. Matador. Retrieved 27 May 2011. 
  7. ^ Bringhurst, Robert (2004). The Elements of Typographic Style (3 ed.). Washington and Vancouver: Hartley & Marks. p. 28. ISBN 0881792063. "2.1.4 Use a single word space between sentences. In the nineteenth century, which was a dark and inflationary age in typography and type design, many compositors were encouraged to stuff extra space between sentences. Generations of twentieth century typists were then taught to do the same, by hitting the spacebar twice after every period [full stop]. Your typing as well as your typesetting will benefit from unlearning this quaint Victorian habit. As a general rule, no more than a single space is required after a period, colon, or any other mark of punctuation" 
  8. ^ Schriver, Karen (1997). Dynamics in Document Design: Creating Text for Readers (1 ed.). New York: Wiley. p. 502. ISBN 9780471306368. "Use one space (not two) after these punctuation marks [sc. period, question mark, exclamation point, or colon], as the practice of using two spaces is just another holdover from using a typewriter." 
  9. ^ Strauss, Jane (2007). "Spacing with Punctuation". The Blue Book of Grammar and Punctuation: An Easy-to-Use Guide with Clear Rules, Real-World Examples, and Reproducible Quizzes (10 ed.). Jossey-Bass. p. 176. ISBN 9780470222683. Retrieved 2010-04-25. "Rule 1. With a computer, use only one space following periods, commas, semicolons, colons, exclamation points, question marks, and quotation marks. The space needed after these punctuation marks is proportioned automatically. With some typewriters and word processors, follow ending punctuation with two spaces when using a fixed-pitch font." 
  10. ^ "2.49 Leading and spacing". The GPO Style Manual (30 ed.). Washington: The U.S. Government Printing Office. 2008. p. 469. ISBN 9780160818127. Retrieved 2010-04-25. "A single justified word space will be used between sentences. This applies to all types of composition." 
  11. ^ "FAQ: How many spaces should I leave after a period or other concluding mark of punctuation?". MLA Handbook for Writers of Research Papers (7 ed.). Modern Language Association. 2009. p. 292. ISBN 978-0-87352-297-7. Retrieved 2010-04-25. "Publications in the United States today usually have the same spacing after a punctuation mark as between words on the same line. Since word processors make available the same fonts used by typesetters for printed works, many writers, influenced by the look of typeset publications, now leave only one space after a concluding punctuation mark. In addition, most publishers' guidelines for preparing electronic manuscripts ask authors to type only the spaces that are to appear in print." 
  12. ^ "FAQ: How many spaces should I leave after a period or other concluding mark of punctuation?". The Chicago Manual of Style (7 ed.). University of Chicago Press. 2009. p. 292. ISBN 9780873522977. Retrieved 2010-04-25. "Publications in the United States today usually have the same spacing after a punctuation mark as between words on the same line. Since word processors make available the same fonts used by typesetters for printed works, many writers, influenced by the look of typeset publications, now leave only one space after a concluding punctuation mark. In addition, most publishers' guidelines for preparing electronic manuscripts ask authors to type only the spaces that are to appear in print." 
  13. ^ "The Chicago Manual of Style Online (Q&A: One Space or Two?)". University of Chicago Press. 2003. Retrieved 2010-04-25. "The view at CMOS is that there is no reason for two spaces after a period in published work. Some people, however—my colleagues included—prefer it, relegating this preference to their personal correspondence and notes. I’ve noticed in old American books printed in the few decades before and after the turn of the twentieth century (ca. 1870–1930 at least) that there seemed to be a trend in publishing to use extra space (sometimes quite a bit of it) after periods. And many people were taught to use that extra space in typing class (I was). But introducing two spaces after the period causes problems: (1) it is inefficient, requiring an extra keystroke for every sentence; (2) even if a program is set to automatically put an extra space after a period, such automation is never foolproof; (3) there is no proof that an extra space actually improves readability—as your comment suggests, it’s probably just a matter of familiarity (Who knows? perhaps it’s actually more efficient to read with less regard for sentences as individual units of thought—many centuries ago, for example in ancient Greece, there were no spaces even between words, and no punctuation); (4) two spaces are harder to control for than one in electronic documents (I find that the earmark of a document that imposes a two-space rule is a smattering of instances of both three spaces and one space after a period, and two spaces in the middle of sentences); and (5) two spaces can cause problems with line breaks in certain programs. So, in our efficient, modern world, I think there is no room for two spaces after a period. In the opinion of this particular copyeditor, this is a good thing." 
  14. ^ "Chapter 5. Manuscript Preparation and Sample Papers to be Submitted for Publication". Publication Manual of the American Psychological Association (aka APA Style) (5 ed.). Washington: American Psychological Association. 2001. p. 439. ISBN 9781557987907. Retrieved 2010-04-25. "5.11 Spacing and Punctuation: Space once after all punctuation as follows: after commas, colons, and semicolons; after punctuation marks at the end of sentences; after periods that separate parts of a reference citation; and after the periods of the initials in personal names (e.g., J. R. Zhang). Exception: Do not use space after internal periods in abbreviations (e.g., a.m, i.e., U.S.)" 
  15. ^ Style Manual: for Authors, Editors and Printers (aka AGPS Style) (6 ed.). Stafford, Australia: Wiley Australia, The Commonwealth Government of Australia Printing Office. 2002. p. 117. ISBN 978-0-7016-3647-0. Retrieved 2010-04-25. "In typewritten (as distinct from typeset) material, it was customary to place two spaces after a colon, semicolon, full stop or other sentence closing punctuation. Programs for word processing and desktop publishing offer more sophisticated, variable spacing, so this practice of double spacing is now avoided because it can create distracting gaps on a page." 
  16. ^ Mergenthaler Linotype Company (1940). Linotype Keyboard Operation: Methods of Study and Procedures for Setting Various Kinds of Composition on the Linotype. Mergenthaler Linotype Company.  cited in Mark Simonson (5 March 2004). "Double-spacing after Periods". Typophile. Typophile. Retrieved 5 April 2010. 
  17. ^ Eijkhout, Victor (2008), TeX by Topic, A TeXnician's Reference (pdf), Lulu, pp. 185–188 
  18. ^ Felici, James (2003). The Complete Manual of Typography: A Guide to Setting Perfect Type. Berkeley, CA: Peachpit Press. p. 80. ISBN 0-321-12730-7. ; Fogarty, Mignon (2008). Grammar Girl's Quick and Dirty Tips for Better Writing (Quick and Dirty Tips). New York: Holt Paperbacks. p. 85. ISBN 978-0-8050-8831-1. ; Straus, Jane (2009). The Blue Book of Grammar and Punctuation: An Easy-to-Use Guide with Clear Rules, Real-World Examples, and Reproducible Quizzes (10th ed.). San Francisco, CA: Jossey-Bass. p. 52. ISBN 978-0-470-22268-3. 
  19. ^ Truss, Lynn (2004). Eats, Shoot & Leaves: The Zero Tolerance Approach to Punctuation. New York: Gotham Books. p. 25. ISBN 1-59240-087-6. 
  20. ^ Bringhurst, Robert (2004). The Elements of Typographic Style (3.0 ed.). Washington and Vancouver: Hartley & Marks. pp. 29–30. ISBN 0-88179-206-3. 
  21. ^ a b The International System of Units (SI) (8 ed.). International Bureau of Weights and Measures (BIPM). 2006. p. 133. .
  22. ^ "Wikipedia: Manual of Style (dates and numbers)". Section 'Units of measurement': Wikipedia. Retrieved 28 January 2011. 
  23. ^ The Unicode Standard ver. 5.2.0 – section 6.2 table 6-2, and section 16.2 Line and Word Breaking
  24. ^ Gillam, Richard (2002). Unicode Demystified: A Practical Programmer's Guide to the Encoding Standard. Addison-Wesley. ISBN 0-201-70052-2. 
  25. ^ "Character design standards – space characters". Character design standards. Microsoft. 1998–1999. Retrieved 2009-05-18. 
  26. ^ The Unicode Standard 5.0, printed edition, p.205
  27. ^ ISO/IEC 10646-1:1993/FDAM 29:1999(E)
  28. ^ "General Punctuation" (PDF). The Unicode Standard 5.1. Unicode Inc. 1991–2008. Retrieved 2009-05-13. 
  29. ^ 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. 
  30. ^ "Network.IDN.blacklist chars". MozillaZine. 2009-02-24. Retrieved 18 September 2010. 
  31. ^ "3.3.3 Attribute-Value Normalization". Extensible Markup Language (XML) 1.0 (Fifth Edition). World Wide Web Consortium. 
  32. ^ "9.1 White space". W3CHTML 4.01 Specification. World Wide Web Consortium. 

Further reading[edit]

  • Saenger, Paul (1997). Space Between Words: The Origin of Silent Reading. Stanford, Calif: Stanford University Press. ISBN 9780804726535. OCLC 35548786. 

External links[edit]