Double spacing at the end of sentences is a typographical convention that was historically practiced in countries using a Latin-derived alphabet. Two spaces were inserted following the terminal punctuation of a sentence (period, question mark, exclamation point). It has sometimes been termed English spacing. Since the mid-1990s, it has often been termed French spacing, although that term has traditionally referred to the practice of single spacing.
In the past, a double space was generally used after a sentence in typewritten copy,[1][2][3] and its use also for printed and published work was based on the rationale that the increased spacing between sentences facilitated readability in monospaced fonts.[4] There are those who continue to use the double space after the concluding punctuation of a sentence, regardless of font type, due to personal preferences – for example, those who were taught to double-space between sentences in a typing class.[5]
Modern book publishers, journals, and periodicals, however, almost universally use the single-space convention in published work.[6][7] The use of a double space after a sentence has reversed nearly completely, primarily because of the widespread use of proportional fonts.[8][9] Some style guides still permit the use of the double space convention for draft written work, based on the writer's preference.
The consensus within U.S. and international style guides that use a Latin-derived alphabet as a language base, is to prescribe or recommend the use of a single space after concluding punctuation in writing and publications. Some style guides permit the use of a double space in certain circumstances if preferred by the writer. No known U.S. or international style guide currently prescribes the use of a double space after concluding punctuation for final or published work.
A widely-used United Kingdom style guide, the MHRA Style Guide, states that "Double spaces should not be used in normal text, and should be eliminated from your copy before submission. In particular, type only a single space between the end of a sentence and the first character of the next, and following major puntcuation marks such as colons and semicolons."[10] This style guide is available and widely used in the United States as well.
The 6th edition of the Style Manual: For Authors, Editors and Printers, reprinted in 2007, is the latest edition of the manual published beginning in 1966 by the Commonwealth Government Printing Office. Editions 2-5 were "published by the Australian Government Publishing Service" between 1972 and 1994. The 6th edition was "revised for the Commonwealth by a consortium of communications and publishing professionals." In the section "Spacing after punctuation" the manual stipulates that one space, not two, is always used after a full stop or other "sentence-closing punctuation." It further asserts that "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.[11]
The Canadian Style, A Guide to Writing and Editing is a widely-used Canadian writing style guide. As the official languages of Canada include both English and French, this manual provides writing conventions in both languages. Its most recent edition states that "in English there is no space before and one space after a punctuation mark."[12] The exceptions noted do not include additional spacing after a period (or "full stop"), question mark, or exclamation mark.[13] In the "French Typographical Rules" chapter, the manual's spacing rules dictate the use of a single space after periods, question marks, and exclamation marks. Double spacing is not allowed following any punctuation for the French language rules, with no exceptions.[14]
The 2006 German language style guide Empfehlungen des Rats für deutsche Rechtschreibung or "Recommendations and Advice for German Orthography" does not address the use of spacing after the terminal punctuation of a sentence.[15] However, the manual itself uses one space after terminal punctuation. The absence of a statement regarding this convention is likely because the two-space convention has not been prescribed in historical German style guides. Additionally, the Duden, the German language dictionary most commonly used in Germany,[16] indicates that the use of a double space following terminal punctuation is incorrect.[17] The Duden was the primary orthography and style guide dictionary in Germany until the German orthography reform of 1996 created a multinational council for German orthography for German-speaking countries which is comprised of experts from Germany, Austria, Liechtenstein and Switzerland. The current version of the Duden reflects the most recent opinions of this council.
French style guides continue to specify that sentences should be single-spaced, and that non-breaking spaces should separate text and most punctuation. French-Canadian style guides diverge slightly on punctuation conventions, but not on the use of a single space following the concluding punctuation of a sentence.[18]
The U.S. Government Printing Office (GPO) was authorized by an act of Congress to "determine the form and style of Government Printing."[19] The 2000 and 2008 editions of the Government Printing Office's (GPO) Style Manual are unequivocal in their guidance regarding this convention: "A single justified word space will be used between sentences. This applies to all types of composition." (Paragraph 2.49) The last known official United States government document to specifically prescribe double spaces after concluding puncutation was a 1959 government style guide. It indicated that sentences should use the em space evenly when typeset, defining a double-space as a synonym for an em space.[20]
This convention is corroborated in various governmental style guides such as the U.S. Navy Style Guide which mandates the use of "only one space after all forms of punctuation."[21]
The Chicago Manual of Style is a comprehensive and widely-used style manual for American English writing and publications, and has been called the "standard of the book publishing industry."[22] The 15th edition, published in 2003, prescribes the single-space convention as follows:
6.11 Space between sentences. In typeset matter, one space, not two (in other words, a regular word space), follows any mark of punctuation that ends a sentence, whether a period, a colon, a question mark, an exclamation point, or closing quotation marks.[23]
The online FAQ to the Chicago Manual of Style explicitly states that a "traditional American practice" is to double-space after colons and periods but then reiterates that, "This practice is discouraged by the University of Chicago Press."[24]
The Turabian Style is widely used in academic writing. The 7th Edition, published in 2007, stipulates that the use of periods, question marks, and exclamation points as "terminal punctuation" to end a sentence should be followed by a single space.[25]
The Modern Language Association (MLA) tolerates either one or two spaces after the "concluding punctuation marks" of a sentence. However, a 2009 statement by the MLA online notes that it expressly uses a single space after concluding punctuation in its MLA writing style examples. This statement also clarified its position on final work for publication in that "Publications in the United States today usually have the same spacing after a punctuation mark as between words on the same line," and "publishers' guidelines for preparing electronic manuscripts ask authors to type only the spaces that are to appear in print."[26]
The APA style guide is a widely-used style guide that is favored by the social sciences in the United States. The current guidance from the American Psychological Association (APA) as of July 2009 is a recommendation to use two spaces for draft manuscripts and work.[27] This recommendation does not apply "to the published, or final version, of a work," where the spacing convention is determined by the publication designer.[28] The APA also notes that "the usual convention for published works remains one space after each period."[29]
Although earlier editions of the Publication Manual of the American Psychological Association provide for the use of a single space following the terminal punctuation of a sentence, the widely-criticized 6th edition,[30][31] published in 2009, changed the convention to two spaces.[32] Soon after the publication of the 6th Edition, the American Psychological Association published nineteen pages of corrections for academic papers online,[33] as well as eight pages of online corrections called "Errors in APA Style Rules" for the 6th Edition prior to issuing a corrected second printing of the 6th Edition in late 2009. The corrections included a revision for the use of a double-space after the terminal punctuation of a sentence to a recommendation for the use of two spaces in draft manuscripts only.[34] Since U.S. publishers of print media typically use the single space convention, this means that any drafts prepared with the double-space convention would have to be converted to the single space convention for final publication.[35] APA notes that the practice of publishers removing extra spaces from a manuscript prior to publication "is a routine part of the manuscript preparation process here at the APA."[36]
The 2006 edition of the Style Manual for Political Science, published by the American Political Science Association, notes that "One space, not two, should follow all punctuation that ends a sentence. This includes periods, colons, question marks, exclamation points, and closing quotation marks."[37]
The 2006 version of this widely-used United States guide to legal citations does not address spacing after the terminal puncutation of a sentence although it does provide various single-space conventions within citation text. A key statement in this guide, which addresses possible preferential differences between courts that require document submissions, notes that "Many state and federal courts promulgate local citation rules, which take precedence over Bluebook rules in documents submitted to those courts."[38] The Blue Book itself uses the single space convention after terminal punctuation within its text.
The latest edition of The Redbook: A Manual on Legal Style, published in 2006, directs users to use "one space between words and one space after punctuation marks (including colons and periods)." The manual clarifies its reasons for this convention in that "The custom during the reign of the typewriter was to insert two spaces between sentences" due to the use of monospaced fonts that are not effective at creating readable text. It indicates that users could continue the use of two spaces if using a typewriter "or the Courier font," and espouses the advantages of widely-available proportional fonts which are degraded by the use of two spaces after terminal punctuation.[39]
The 2004 edition of the Associated Press Stylebook calls for a single space after colons and following the terminal punctuation of a sentence.[40]
The 2nd edition of The Copyeditor's Handbook: A Guide for Book Publishing and Corporate Communications, published in 2006, states that "You should also delete any extra word spacing before or after punctuation marks. The conventions are: One space follows a sentence-ending punctuation mark."[41]
The Gregg Reference Manual is a style manual intended for business professionals. The most recent edition, published in 2005, provides a comprehensive treatment of its guidance for the rules of spacing within and outside of sentences. The manual's punctuation spacing section identifies that "The standard for proportional fonts has always been the same: use only one space between the period and the start of the next sentence" and "now that the standards of desktop publishing predominate, the use of only one space after the period is quite acceptable with monospace fonts."[8]
On the convention described in this article, the manual further clarifies that "As a general rule, use one space at the end of a sentence, but switch to two spaces whenever you feel a stronger visual break between sentences is needed." The manual identifies specific instances when only one space is to be used between sentences such as "If you are preparing manuscript on a computer and the file will be used for typesetting, use only one space and ignore the issue of visual appearance." The manual indicates that writers should also "Use only one space if the text will have justified margins," and "If the manuscript has already been typed with two spaces at the end of every sentence, use the Replace function to change two spaces to one space throughout." The author caveats these general and specific rules for the use of one space with certain instances when a writer may want to use two spaces between sentences. The examples given are: when one space "may not provide a clear visual break between sentences," if an abbreviation is used at the end of a sentence, or when some very small proportional fonts (such as 10-point Times New Roman) are used. The manual clearly places an emphasis on the use of white space to create a pleasing document by noting spacing rules that differ from established norms such as the use of two spaces before opening a parenthesis, after closing quotation marks, and after opening single quotation marks inside of sentences.[42]
The 2007 edition of this medical style guide does not provide specific guidance on the use of this convention. However, users of this style manual can gain insight on the recommended procedures to ensure consistent application of this convention through various sections within. In a chapter called "Harness the Potential of Computers and the Internet," the manual indicates that "Most, if not all, writers today use computers and can capitalize on a variety of built-in tools standard in most word-processing programs" and notes that "software programs recognize errors and provide corrections for writers."[43] Additionally, Appendix E lists electronic resources for further clarification on style, grammar and orthography. The style manuals listed are the Chicago Manual of Style which prescribes the use of one space between sentences, the APA style manual which recommends the use of two spaces for draft work and one space for final work, and the Elements of Style which does not provide guidance on this convention.[44]
The 2008 edition of the Web Style Guide does not discuss spacing after the terminal punctuation of a sentence, although it provides a chapter on typography. In this section, the authors assert that "the basic rules of typography are much the same for both web pages and conventional print documents."[45] Although the guide does not specifically recommend against the use of monospaced fonts, only proportional fonts are presented as "common screen fonts" and those "designed for the screen."[46] Finally, although HTML will utilize only one space after the terminal punctuation of a sentence unless the user specifies changes, the authors caution against custom fonts and typefaces because most user's browsers will default to a font defined by their operating system.[47][48]
A number of United States style guides do not provide guidance on this convention, especially those that are smaller in scope and rely on other, more comprehensive, style guides to provide a framework. However, some of these style guides are well-known, including the 4th edition of Strunk and White's The Elements of Style, a widely used general style guide, which is silent in reference to spacing between sentences.[49] Other U.S. style guides that do not address this convention include The Wall Street Journal Essential Guide to Business Style and usage (2002),[50] the Guide to Legal Writing Style (2007),[51] REA's Handbook of English Grammar, Style, and Writing (2009),[52] and the American Sociological Society Style Guide (2007).[53] The Economist Style Guide (2005), published in the United Kingdom, also provides no guidance on this convention.[54] These guides themselves use the conventional single-space rule in their text.
The book, Grammar Girl's Quick and Dirty Tips for Better Writing, states that in the past typewriting used monospace fonts and used two spaces as a result, but "Now that most writing is done on computers it is no longer necessary to type two spaces after a period at the end of a sentence." The author notes that the use of this convention is still technically up to style manuals. She indicates that numerous page designers have contacted her stating that two spaces between sentences leave "unappealing runs of white space," requiring them to edit the pages to remove the extra spaces. Her final recommendation is to use "one space."[55]
The list of studies on this spacing rule is relatively small compared to other studies on the readability and legibility of text. The only recorded studies completed to date are those completed by "Loh, Branch, Shewanown, & Ali (2002), Clinton, Branch, Holschuh, & Shewanown (2003) and Ni, Branch & Chen (2004)" with inconclusive results on the readability or legibility of one rule over the other.[56] The 2002 study was conducted on web-based media only and indicated that "the ‘double space group’ consistently took longer time to complete the on-screen reading task than the ‘single space’ group," but the authors concluded that "there was not enough evidence to suggest that a significance difference exists.[57]
The Gregg Reference Manual, published in 2005, asserts that a single space may not always "provide a clear visual break between sentences," and recommends switching to "two spaces whenever you feel a stronger visual break between sentences is needed."[58]
The Corrections to the First Printing of the Publication Manual of the American Psychological Association, Sixth Edition states that "Spacing twice after punctuation marks at the end of a sentence aids readers of draft manuscripts."[59]
The book About Face: Reviving the Rules of Typography, published in 2004, provides an extensive treatment on spacing within lines of text, providing coverage of many of the points addressed by those that discuss single and double spacing rules:
Close, consistent work spacing will make it easier for the eye to smoothly skip along a line of text with the minimum pauses. Visually, a page of text should appear as an orderly series of thin, horizontal, evenly textured lines, separated by channels of clear space. If the setting is loose, there is a tendency for the texture of these lines to appear uneven, fractured, and, in the worst cases, broken. Persistent use of over-large word spaces...can align with spaces in other lines to create white, vertical 'rivers' through the text. Comprehension will certainly be impaired if the type cannot keep the reader's eye on the line, and a tightly spaced line will greatly help.
Word spaces, preceding or following punctuation, should be optically adjusted to appear to be of the same value as a standard word space. If a standard word space is inserted after a full point or a comma, then, optically, this produces a space of up to 50% wider than that of other word spaces within a line of type. this is because these punctuation marks carry space above them, which, when added to the adjacent standard word spaces, combines to create a visually larger space. Some argue that the 'additional' space after a comma and full point serves as a 'pause signal' for the reader. But this is unnecessary (and visually disruptive) since the pause signal is provided by the punctuation mark itself. [60]
Many Americans have polarized views on the use of the double space after a sentence, due mainly to the fact that they were taught to use the double space rule in typing class. Many, notably those in "printing, design, editing and advertising," have opinions on typography but even most textbooks on typography rely on anecdotal evidence, rather than empirical evidence provided by scientific studies.[61] Since there are few studies on the readability and legibility of inter-sentence spacing, the public continues to maintain strong feelings on both sides.
Those who argue for the use of the single space following a sentence point to the fact that the single space is the modern convention for final and published print media, as well as on the World Wide Web because HTML does not permit spaces beyond a single-space. They argue that the use of the double-space could create "rivers" of white space on a page, which might decrease readability due to the necessity for the eye to skip from one sentence to the next. Additionally, since publishers typically require manuscripts to be sumbitted with single-spaces after sentences, those who write with double-spaces will either have to remove the single space before submission, or copyeditors will have to remove them prior to publication.
Those who argue for the use of the double space following a sentence point out that additional space following sentences could increase readability by providing an extra "break" between sentences.[62] Some state that sentences that are typeset too closely together could negatively impact readability and legibility without extra space after terminal punctuation. Many with strong feelings on this subject object to the change to single-spacing in final and published print media on the grounds that the habit of double-spacing is too deeply ingrained in them to change.
Historically, typesetting in all European languages has a long tradition of using spaces of varying widths for the express purpose of enhancing readability. American, English, French, and other European typesetters' style guides—also known as printers' rules—specified spacing rules which were all essentially identical from the 18th century onwards.
Following the widespread adoption of the typewriter, French spacing and English spacing were terms describing French-language typists' and English-language typists' differing standardized typewriter approximations with single-width spaces of traditional typesetters' spacing rules:
Starting with Gutenberg, European typesetting (continental and British Isles) used a wide range of various width spaces and alternate-width letter and ligature choices in order to enhance readability and appearance and to facilitate justification. Alternate-width letters and ligatures were quickly discarded as requiring too much effort for normal use (but remain best-practice among sophisticated typesetters), but the 15th-century attempt to further discard alternate-width spaces was quickly rejected by readers as too difficult for normal reading. Typography then standardized on an essentially common set of spacing rules, using multiple width spaces.[citation needed]
Multiple width spaces were for several centuries universally retained even in high-volume commercial printing. Their usage formed traditional typesetting's spacing rules.[citation needed]
Early English-language style guides such as Jacobi in the UK[65][66] and MacKellar, Harpel, Bishop, and De Vinne in the USA[67][68][69][70] specified that sentences should be em-spaced, and that words should be 1/3 em spaced (occasionally 1/2 em). This remained standard for quite some time. For example, MacKellar's The American Printer was the dominant style guide in the US at the time and ran to at least 17 editions between 1866 and 1893, and De Vinne's The Practice of Typography was the undisputed global authority on English-language typesetting style from 1901 until well past Dowding's first formal alternative spacing suggestion in the mid-1950s. Further, both the American and the UK style guides also specified that spaces should be inserted between punctuation and text. (It should be noted in passing that the MacKellar guide described these as hairspaces but itself used a much wider space than was then commonly regarded as a hairspace, apparently matching Jacobi's widely accepted 1890 standardization on the 1/5 em space.[67])
Different width spaces were used for various specific purposes. In general, as well as separating words and sentences:
Additionally, spaces were (and still are today) varied proportionally in width when justifying lines, originally by hand, later by machine, now usually by software. That is, a justified line containing for example em spaces and en spaces would have both types of spaces lengthened, but their relative proportions would be retained.
The spacing differences between traditional typesetting and modern mass-production commercial printing are easily observed by comparing two different versions of the same book, from the Mabinogion:
The modern version demonstrates late 20th-century mass-production commercial practice. The older version demonstrates thin-spaced words but em-spaced sentences—effectively, double-spacing. It also demonstrates spaces around punctuation according to the rules above and equivalent to French typesetting today.
The American Declaration of Independence (1776) clearly shows wider spacing after sentences, typically double-width or even wider. It also shows wider spacing after some commas, apparently when separating semantically significant phrases and clauses.
The introduction of the typewriter allowed ordinary people to create typewritten text without the requirement for professional typesetting equipment or professional typesetters.
With the typewriter, French and English typing standards diverged, adopting alternative typewriter approximations of the essentially common typesetting standard.
The one exception English typists made was that a colon or semicolon should be followed and preceded by single spaces.
The outcome was that French spacing had single spaces between sentences but a great many additional em spaces between text and punctuation (e.g., spaces precede semicolons, exclamation marks, and question marks, and are inserted between text and enclosing quotation marks), while English spacing had no spaces between text and punctuation but double-spaces (two notionally half-em spaces equals one notional em space) following colons and semicolons and between sentences.[64][72]
These approximations were taught and used as the standard typing techniques in French- and English-speaking countries, respectively.[73] For example, T.S. Eliot typed rather than wrote the manuscript for his classic The Waste Land between 1920 and 1922, and used only English spacing throughout: double-spaced sentences.[74]
Typesetters continued to follow the original standards, but increasingly started to adopt the typists' approximations as their typesetting style, particularly in America but also in the UK and France.[75]
The reasons were predominantly commercial rather than stylistic. A key change in the publishing industry from the mid-19th century to the mid-20th century was the enormous growth of mass-produced books and magazines. Increasing commercial pressure to reduce the costs, complexity, and lead-time of printing deeply affected the industry, leading to a widening gap between commercial printing and fine printing.[76] For example, T. S. Eliot's The Waste Land was originally published by a high-volume commercial printer according to its house rules and it was not until its third publication that Eliot was satisfied with its typesetting.[77]
The underlying reasons were:[76]
Where before the First World War virtually all English-language books were printed following standard typesetters' spacing rules, by the end of the Second World War most American books and an increasing proportion of English books were printed following the typewriter's English spacing approximation rules.[78][79][80] By the 1960s it was rare even in England for ordinary English-language books to be printed using standard typesetters' spacing rules.
Around World War II, with an increase in high-volume low-cost mass-produced printing (e.g., newspapers, pulp-novels, magazines) the practice arose of single-spacing between sentences and after colons and semicolons, to the point of being standard commercial practice in mass-print-runs from the 1950s onwards in America, although the practice was adopted more slowly in other English-speaking countries. The practice moved over time into the more expensive works.
The English spacing approximation was retained in higher quality (and higher cost) printing. For example, the US government's official style guide mandated its use in 1959 for all government documents regardless of printing method:[20]
To aid readability, an em quad (or double-space) is used at the end of a sentence. This applies to all types of composition, and includes Teletypesetter, reproduction, and other printing. Unless otherwise specified, this rule will apply.
By the time of the creation of the computer typesetting program TeX, and at least up until 1993,[81] this was still known even in America as English spacing (sometimes: American typewriter spacing). For example, people wishing to produce only single spaces between sentences in TeX need to switch on the French spacing output option.
The introduction of non-commandline DTP software by the Macintosh in the mid-1980s and its subsequent widespread adoption eliminated the previous cost-restriction that had driven the switch to single-spacing. There was no longer any material marginal cost associated with typesetting double-spaces, or even multiple-width spaces.
Despite this, resistance to double-spaced sentences started to grow among English-language professional designers and typographers as they became more directly involved with typesetting. Traditional French typists' rules continued to be the uncontested norm in French-speaking countries,[82] but English spacing became increasingly deprecated in English-speaking countries.
Additionally, there has been a designer-led trend towards closer-fitted text in general.[83][84][85] For example, an increasing number of computer font design guidelines now recommend use of quarter-em spaces rather than third-em spaces. With regard to spacing, modern designers are retracing the steps of the 19th-century design-led typographer William Morris. Morris rejected the restrictions of commercial typesetting which at the time demanded traditional typesetting's spacing rules, and, declaring a "rage for beauty", advocated close-set type and dark "color" (lack of whitespace, creating uniformity of appearance). But this "rage for beauty" did not not necessarily translate to reader comprehension. The reason Donald Knuth gave for creating the TeX typesetting system was his dismay on receiving the proofs of a new edition of his book The Art of Computer Programming at the unreadability of the then new close-fitted phototypesetting technology, which he described as "awful" due to its "poor spacing".[86][87] The leading style guides of Morris's time documented that readers of the time had the same reaction to Morris's output as Knuth did later to phototypesetting's output. De Vinne, for example, wrote in The Practice of Typography:
Printed words need the relief of a surrounding blank as much as figures in a landscape need background or contrast, perspective or atmosphere.(p.182) White space is needed to make printing comprehensible.(p.183)
And in Modern Book Composition he wrote:
Unleaded and thin-spaced composition is preferred by the disciples of William Morris, but it is not liked by the average reader, who does need a perceptible white blank between words or lines of print. During the fifteenth century, when thin leads and graduated spaces were almost unknown and but little used, the reading world had its surfeit of close-spaced and solid typesetting (p.105)
By the mid-1990s, the term French spacing was observed to be occasionally used in America to refer to English spacing. The earliest use of this inversion was apparently 1994 by the University of Chicago Press.[88] By the mid-2000s this usage had been widely replicated on the Internet.
It is not clear why this reversal occurred.
An American publishing consultant to the legal profession (which uses double-spacing in formal documents in most English-speaking countries) noted in 2007 that French typography conforms to the original meaning of French spacing rather than the revised American meaning:[93]
As noted in Microsoft's Character Design Standard (5 of 10): Space Characters for Latin 1: "In digital fonts there are only two kinds of space characters supported by most computers, the space and the no-break space." This means that moving to computers has not altered the situation created by the typewriter:[citation needed] if the typist wishes to separate sentences more clearly, or to use the English spacing approximation of the standard typesetters' spacing rules, the lack of multiple-width spaces still requires use of multiple spaces on computers, just as on typewriters.
Some computer typesetting technologies discourage the use of double-spacing (e.g., HTML, XML, SGML), whereas others encourage or create it (most notably TeX and LaTeX).
Some computer text editors, such as Emacs and vi, originally relied on double-spacing to recognize sentence boundaries. By default, Emacs will not break a line at a single space preceded by a period, but this behaviour is configurable (with the option sentence-end-double-space). There are also functions to move the cursor an entire sentence forward or backward which rely on double-spaced sentences. In Vim the joinspaces setting indicates whether extra spaces are inserted when joining lines together. The GNU Coding Standards still recommend using two spaces,[94] to accommodate the default behavior of traditional text editors.
The optional Emacs mode LaTeX provides a toggling option French-LaTeX-mode which if set to French automatically inserts additional and correctly-breaking spaces around punctuation, but does not create double-spacing between sentences or after colons or semicolons.[95][96]
Web browsers follow the HTML display specification and for programmers' convenience ignore runs of white space when displaying them.[97][98] In order to force a web browser to display multiple spaces, a special character sequence (such as    for an en-space followed by a thin space,   for an em-space, or for two successive spaces) must be used.[99]
The typesetting software TeX also treats input runs of whitespace as a single space, but uses a heuristic to recognize sentence endings and typesets the spaces after them slightly wider than a normal space. These elongated spaces can grow faster than regular spaces (and shrink less) when the text is justified. Spaces after some other punctuation marks, such as commas and colons, also have this additional flexibility for justification though their natural size is the same as a regular space. Contrary to the relatively recent Americanism, Knuth uses the terms English spacing and American typewriter spacing to describe this: he named the TeX macro to disable the automatic enlarging of space after the end of a sentence \frenchspacing, whereas wider-spacing is the default (or can be explicitly enabled with \nonfrenchspacing).[citation needed]
Microsoft Word similarly uses a heuristic to recognize sentence endings. It does not distinguish between single- and double-space sentence breaks; it will allow the user to enter as many spaces as desired, and it will display or print as many spaces as are entered. However, the grammar and style options of the program can be set to automatically single or double-space a sentence, per user preference. The early bug it had with inserting linebreaks between the two spaces of a double-spaced sentence break has been fixed since at least Word 97.
Many Type 1 Postscript fonts do not have a non-breaking space in their character set. When the user tries to insert a non-breaking space using these fonts, the OS substitutes the default (breaking, single-width) space. This frequently causes problems for French typists since they make heavy use of the non-breaking space.
ASCII and similar early character encodings provide only a single space, which is breaking and fixed-width (the particular width specified by each particular output font).
EBCDIC, although earlier than ASCII, provided a breaking fixed-width space (SP), a non-breaking fixed-width space (RSP: "Required SPace"), and an alternate-width non-breaking fixed-width space intended for use in numeric lists with fixed-width (but not necessarily em-width) digits (NSP: "Numeric SPace").
HTML and Unicode can both record runs of consecutive spaces, and also explicitly provide the capability to record multiple-width spaces and breaking and non-breaking spaces.
HTML provides 4 variations on space width and 1 fixed-width non-breaking space, which are: <space>,  ,  , and   (all breaking); and (non-breaking). Note that <space> will equal   in a typewriter font but will vary according to the font designer's specification in all other fonts, whether proportional or monotype. Note that the HTML standard also specifies Display behaviour, not just character encoding, so web browsers following the HTML standard will collapse multiple <space>s to a single <space>. Non-browser apps which use HTML encoding will not necessarily behave this way at display-time, e.g. later versions of MS Word.
Unicode provides 15 variations on space width and breakability, including: THIN SPACE   and NARROW NO-BREAK SPACE  .[100][101][102]
Some confusion exists within the Unicode standard of how to apply these under various spacing rules:[103]
The following demonstrates the effect of various approaches on your browser ...:
- No space before the exclamation mark!
- A no-break space before the exclamation mark !
- A THIN SPACE (
 ) before the exclamation mark !- A NARROW NO-BREAK SPACE (
 ) before the exclamation mark !- A small-formatted no-break space before the exclamation mark !
Following the original ideal (calligraphy), typesetting explicitly provided for a huge range of spacing options designed to maximize readability while still allowing visually attractive text. Gutenberg, for example, used up to 14 different widths for each letter and ligature and used an effectively unlimited range of space widths. This was wholly manual work however, taking a long time and requiring high skill. Since then, most of this space variation has fallen out of use.
Digital DTP technology in the last two decades has brought a renaissance in cost-effective typesetting capability. There is no longer a material marginal cost associated with typesetting double-spaces, or even multiple-width spaces.
French spacing and English spacing in a typesetting environment can be viewed as either or both of: a substitute for full typesetting, and typists' input "hints" to typesetters' output; in both cases imitating and approximating at input time the results of traditional typesetting's standard and ideal output.[104]
In order for users to enter typesetter-emulating text without resorting to approximations such as French spacing or English spacing, while still allowing any later typesetter full control over spacing design decisions, text entry technology must allow at least the following spaces to be easily entered by untrained users, including text-entry software inferring them[105][95][106] from predefined typographic standards on input just as TeX infers them on output:
stock | retire | vm
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