Double spaced sentences

Double spacing at the ends of sentences is a typographical convention that 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.

Overview

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:
* "French spacing" inserted spaces around most punctuation marks, but single-spaced after sentences, colons, and semicolons. ["Lexique des règles typographiques en usage à l’Imprimerie nationale", 3ème édition, Imprimerie nationale, 1993]
* "English spacing" removed spaces around most punctuation marks, but double-spaced after sentences, colons, and semicolons. [Nelson, Julius (1949) "Stylebook for Typists" New York: Gregg Publishing Company]

Context: spacing rules

Background

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.

Multiple width spaces were for several centuries universally retained even in high-volume commercial printing. Their usage formed traditional typesetting's spacing rules.

Traditional English typesetting's spacing rules

Overview: general usage and standard space definitions

Different width spaces were used for various specific purposes. In general, as well as separating words and sentences:
* spaces separated most punctuation marks from their associated text, with some exceptions:
**no space preceded a comma or a full stop (period)
**(increasingly frequently) no space preceded a closing quotation mark following a period or comma
**a long dashLong dashes were unspaced but have disappeared from modern typography. They were typically 1.5 ems in length. The modern equivalent would be an em dash followed by an en dash. Em dashes and en dashes conformed to normal punctuation spacing rules: a narrow space was inserted between the dash and the text.] "(shorter dashes were always space separated)" normally had neither preceding nor following space
* spaces following words or punctuation were subject to line breaks
* spaces between words and closely associated punctuation were non-breaking

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.

Examples of traditional double-spacing

British

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:
#1894: [http://books.google.com/books?id=vyKnNaPhmXAC&pg=PA36&lpg=PA36&dq=game+of+%22badger+in+the+bag%22&source=web&ots=e10KJy1tkl&sig=MpTR-vFkB6lsCD_6irwvM9BaSFg#PPA36,M1 the Badger-in-the-bag game] —traditional typesetting spacing rules: double-spacing
#1976: [http://books.google.com/books?id=4cSMy-lJwNEC&pg=PA58&lpg=PA58&dq=game+of+%22badger+in+the+bag%22&source=web&ots=hdC1HqhNGr&sig=gNtbVmwI1Q5idPpINkq8zyXQUqA the Badger-in-the-bag game] —modern mass-production commercial printing: single-spacing

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.

American Declaration of Independence

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.

French and English spacing

Origin: the typewriter

The introduction of the typewriter allowed ordinary people to create typewritten text without the requirement for professional typesetting equipment or professional typesetters.

French spacing rules and English spacing rules

With the typewriter, French and English typing standards diverged, adopting alternative typewriter approximations of the essentially common typesetting standard.
* French typists used only a single em space in all circumstances.
* English typists used a single space between words and a double space between sentences.

The once 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 colons, 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. [Lexique des règles typographiques en usage à l’Imprimerie nationale, 3ème édition, Imprimerie nationale, 1993] [Nelson, Julius (1949) "Stylebook for Typists" New York: Gregg Publishing Company]

These approximations were taught and used as the standard typing techniques in French- and English-speaking countries, respectively. [Igot, Pierre (2006) " [http://www.betalogue.com/2006/06/21/microsoft-word-and-non-breaking-spaces-french-typography-101/ Microsoft Word and non-breaking spaces: French typography 101] "] 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. [Gordon, Lyndall (1999) "T. S. Eliot: An Imperfect Life" W. W. Norton & Company; 1st American ed edition]

Evolution of typing, typesetting, and French and English spacing

Influence of typewriter approximations

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. [see "Le Monde" in: Set in Style (2007) " [http://misterthorne.org/set_in_style/2007/01/25/sur-franais-espacement/ sur espacement français] "]

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. [Keefe, H. J. (1939) "A Century in Print" London: Hazell Watson & Viney, Ltd.] 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. [Rainey, Lawrence (2005) "The Annotated Waste Land with Eliot's Contemporary Prose" New Haven: Yale University Press]

The underlying reasons were: [Keefe, H. J. (1939) "A Century in Print" London: Hazell Watson & Viney, Ltd.]
* ease and speed, since far less physical type and more importantly far less skilled effort was required
* cost, since fewer man-hours were required and the condensed text required less paper. The bulk of the cost saving was typesetting-related rather than paper-use-related
* cultural, since new typesetters (and readers) had grown up with typewriters and the standard typists' spacing approximations of good typesetting

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. [e.g., standard typesetters' spacing rules: Linklater, Eric (1954) "A year of space" The Reprint Society, London] [e.g., English spacing: Gordon, Richard (1955) "Doctor in the House; Doctor at Sea" The Reprint Society, London] [e.g., English spacing: Leslie, Doris (1956) "Peridot Flight" The Book Club, London] By the 1960s it was rare even in England for ordinary English-language books to be printed using standard typesetters' spacing rules.

After World War II

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 moved 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: [United States Government Printing Office Style Manual (1959), paragraph 2.36.1]

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 computer typesetting program TeX's creation, and at least up until 1993, [Siebenmann, Laurent (1993) " [http://www.tug.org/TUGboat/Articles/tb14-3/tb40siebenmann.pdf A Format Compilation Framework for European Languages] ", TUGboat, Volume 14, No. 3 – Proceedings of the 1993 Annual Meeting] 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.

Desktop publishing

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, [" [http://cprp.ca/guide.php?category_name=autres-ressources#english FRENCH STYLE GUIDE – A Reference Document] " (2001) Nova Scotia Department of Education] but English spacing became increasingly deprecated in English-speaking countries.

Additionally, there has been a designer-led trend towards closer-fitted text in general. [Dowding, G. (1954) "Finer Points in the Spacing and Arrangement of Type" Wace & Co.: London.] [Felici, James (2002) "The Complete Manual of Typography" Adobe Press] [Bringhurst, Robert (2004) "The Elements of Typographic Style" 3rd ed., Hartley and Marks Publishers] 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". [Knuth, Donald (1986) " [http://www.cemi.rssi.ru/cyrtug/win/texbirth.htm Remarks to celebrate the publication of Computers and Typesetting] " Address delivered at the Computer Museum in Boston on May 21, 1986. The full text can be found in TUGboat, 7 (1986), 95–98] [Seroul, Raymond; and Levy, Silvio (1991) "A Beginners Book of TeX" Springer-Verlag, pp 1-2] 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)

Terminology

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. [cite book| url=http://books.google.com/books?id=ewSglB2f7qYC&pg=PA45&ots=6svfxuZIP9&sig=3eTovXfBHZTquOrraLwMzINg9Yk#PPA46,M1 | title=Glossary of Typesetting Terms| first=Richard| last=Eckersley| publisher=University of Chicago Press| year=1994| isbn=0226183718| pages=46| authorlink=Richard Eckersley] By the mid-2000s this usage had been widely asserted on the internet.

It is not clear why this reversal occurred.
*It is possible that the relatively many extra spaces in traditional French spacing were conflated with the double-spaces in traditional English spacing.
*It is possible that the term may be colloquially derived from the professional printing industry. It is relatively difficult to add double-spaces to text that is typeset using a hot metal Linotype machine. Spaces were added to the text using wedges, which automatically fully justified the text, but two normal wedges together introduced problems. A workaround using an en space followed by a thin justifier-space might have been thought of as "fancy" (or "French") and cost extra. [Late Night Engineer (2007) " [http://www.latenightengineer.com/play/french-spacing-css French Spacing] "] [Harris, Sam (of the now-defunct areader.com); quoted in Rhodes, John S. (1999) " [http://www.webword.com/reports/period.html One Versus Two Spaces After A Period] "]
*It is possible that it was an attempt to discourage the practice by labeling it alien. [cite web |url=http://www.dynamicgraphics.com/dgm/Article/28654/ |title=Typographic Details |accessdate=2007-11-07 |last=Haley | first=Allan |date=2006-07] [Martin, Ben (2007.04.02) " [http://www.bmartin.co.uk/archive/2007/04/02/full-stop-space-space/ Full Stop, Space, Space...] (No no no no no no NO. Alright?)"]

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: [Set in Style (2007.01.25) " [http://misterthorne.org/set_in_style/2007/01/25/sur-franais-espacement/ sur espacement français] "] "(emphasis added)"

Readability

The only study on the comparative readability of the spacing conventions has been Colin Wheildon's study "Communicating, or just making pretty shapes?", [Wheildon, Colin A. (1986-2004) " [http://www.amazon.com/dp/1875750223 Communicating or just making pretty shapes – A study of the validity (or otherwise) of some elements of typographic design] " The Worsley Press] , which found empirical support for some design assertions but for others found empirical support for their opposite.

tyle preferences

General preferences

Four main preferences exist today:
* Some authors believe that text using double-spaces between sentences is more readable than text written with only one space after the period. [United States Government Printing Office Style Manual (1959), paragraph 2.36.1] [Margulis, Dick (1999) " [http://www.techwr-l.com/archives/9907/techwhirl-9907-01344.html Space between sentences—Eureka! the source of confusion] " TECHWR-L] [Peters, Tim (2002) in " [http://mail.python.org/pipermail/python-dev/2002-June/025155.html Python-Dev: textwrap.py] " in Python Dev newsgroup/mailinglist] [Wayne (2006.02.28) in " [http://blogs.msdn.com/fontblog/archive/2005/11/03/488794.aspx#540691 FontBlog Typography Tips] "]
* Some authors believe that proportionally spaced fonts have made double-spacing redundant, and that it should only be used in a monospaced (nonproportional) font. [e.g., Rhodes, John S. (1999) " [http://www.webword.com/reports/period.html One Versus Two Spaces After A Period] "] The argument here is that double-spacing was an attempt in a monospaced font to create the effect of proportional fonts' spaces, and that the ready availability now of proportional fonts renders a double-space redundant. However, the width of spacing in a proportional font width is nearly always narrower than an em space.
* Some authors (particularly professional designers or typographers) believe that double-spacing creates an unappealing appearance. [Bringhurst, Robert (2004) "The Elements of Typographic Style" 3rd ed., Hartley and Marks Publishers] [Duggan, Mike (2005) clarifying FontBlog's house position in " [http://blogs.msdn.com/fontblog/archive/2005/11/03/488794.aspx#488867 FontBlog Typography Tips] "] [Bear, Jacci " [http://desktoppub.about.com/cs/typespacing/a/onetwospaces.htm Use One Space Between Sentences — Desktop Publishing Rules on Spacing After Punctuation] " About.com]
* Some authors believe best practice is dependent on the particular typeface being used. [Roselli, Adrian (1999) " [http://evolt.org/node/213 Two Spaces After a Period Isn't Dead Yet] "]

tyle guides

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, still specifying single-spaced sentences but allowing that non-breaking spaces are not needed before question marks, exclamation marks, or semicolons. [" [http://www.cprp.ca/style/#english FRENCH STYLE GUIDE – A Reference Document] " (2001) Nova Scotia Department of Education] An exception is the French daily [http://www.liberation.fr Libération] uses French quotation marks without any spaces.

Early English-language style guides such as Jacobi in the UK [Jacobi, Charles Thomas (1890) "Printing" London: C. Whittingham] [Jacobi, Charles Thomas (1892) "Some Notes on Books and Printing; a Guide for Authors, Publishers, & Others, New and enl. Ed." London: C. Whittingham] and MacKellar, Harpel, Bishop, and De Vinne in the USA [MacKellar, Thomas (1866) "The American Printer: A Manual of Typography, Containing Complete Instructions for Beginners, as Well as Practical Directions for Managing Every Department of a Printing Office" Philadelphia: MacKellar Smiths & Jordan] [Harpel, Oscar (1870) "Harpel's Typograph, or Book of Specimens Containing Useful Information, Suggestions and a Collection of Examples of Letterpress Job Printing Arranged for the Assistance of Master Printers, Amateurs, Apprentices, and Others" Cincinnati Press] [Bishop, Henry Gold (1895) "The Practical Printer: A Book of Instruction for Beginners; a Book of Reference for the More Advanced, 3rd. ed." Albany] [De Vinne, Theodore Low (1901) "The Practice of Typography : correct composition: a treatise on spelling, abbreviations, the compounding and division of words, the proper use of figures and numerals. With observations on punctuation and proof-reading." New York, Century Co.] 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. [MacKellar, Thomas (1866) "The American Printer: A Manual of Typography, Containing Complete Instructions for Beginners, as Well as Practical Directions for Managing Every Department of a Printing Office" Philadelphia: MacKellar Smiths & Jordan] )

The official USA government style guide of 1959 specifies that sentences should be em-spaced even when typeset, and defines a double-space as a synonym for an em-space: [United States Government Printing Office Style Manual (1959), paragraph 2.36.1]

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.

Recently some widely-used American style guides, notably the Chicago Manual of Style, call for a single space after full stops and colons. [" [http://www.chicagomanualofstyle.org/access/intercept.epl?path=/ch02/ch02_sec012.html Line spacing and word spacing] ". Chicago Manual of Style. (subscription required)] [Associated Press (2004) "AP Stylebook" New York: Basic Books, 334-335.] In chapter 6 "Punctuation" section 3 "Typographic and Aesthetic Considerations", for example, the Chicago Manual of Style states:

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.

The FAQ to the Chicago Manual of Style explicitly states that the "traditional American practice" is to double-space after colons and periods but then states that "This practice is discouraged by the University of Chicago Press". [Chicago Manual of Style FAQ " [http://www.chicagomanualofstyle.org/CMS_FAQ/OneSpaceorTwo/OneSpaceorTwo02.html One Space or Two] "]

Designers' style preferences

The reasons offered in support of single spacing are stylistic, reader-centric, and historical.

Historical reasoning asserts that single-spacing is the historical norm and that double-spacing is a typewriter-driven anomaly. Examples include the Font Site's declaration of " [http://www.fontsite.com/Pages/RulesOfType/ROT0997.html The Rules Of Type] ", citing Cavanaugh's "Digital Type Design Guide": [Cavanaugh, Sean; Oyer, Ken (1996) "Digital Type Design Guide: The Page Designer's Guide to Working With Type" Hayden Books.]

Computer software

Overview

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: 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).

Text editors

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. The GNU Coding Standards still recommend using two spaces, [ [http://www.gnu.org/prep/standards/html_node/Comments.html#Comments GNU Coding Standards §5.2 Commenting your work] ] 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. ["French typography" in the Emacs LaTeX mode's included online-help [http://stuff.mit.edu/afs/sipb/project/sipb-old/lib/elisp/info/latex-mode.info-3 Info file: latex-mode.info] ] [ [http://www.netlib.org/bibnet/tools/emacs/ltxmode/ltxmode.dif LaTeX Mode] (1991)]

Web browsers

Web browsers follow the HTML display specification and for programmers' convenience ignore runs of white space when displaying them. [ [http://www.w3.org/TR/html4/struct/text.html#h-9.1 W3C - HTML 4.01: Paragraphs, Lines and Phrases] ] [Web Hypertext Application Technical Working Group (WHAT-WG): [http://whatwg.org/specs/web-apps/current-work Current Work] ] 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. [ [http://www.w3.org/TR/html4/sgml/entities.html#h-24.4 W3C - HTML 4.01: Character entity references in HTML 4] ]

TeX

The typesetting software TeX by also treats input runs of whitespace as a single space, but uses a heuristic to recognize sentence endings and typesets these by default with double-spaces. 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 double-spacing is the default (or can be explicitly enabled with onfrenchspacing).

Microsoft Word

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. The early problem it had with inserting linebreaks "between" the two spaces of a double-spaced sentence break has been fixed since at least Word 97.

Operating systems

Macintosh users cannot choose space length but can enter breaking spaces or non-breaking spaces (option-space) in any program.

Microsoft Windows users and most unix users cannot choose space length and are further restricted to only entering breaking spaces unless particular applications provide explicit French spacing support or an ability to enter non-breaking spaces.

Postscript fonts

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.

Character encodings

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  . [ [http://www.cs.tut.fi/~jkorpela/unicode/guide.html Unicode Guide] ] [ [http://www.unicode.org/unicode/reports/tr14/#DescriptionOfProperties Unicode Standard Annex #14: Line Breaking Properties] ] [Sheerin, Peter K. (2001) " [http://www.alistapart.com/stories/emen/ A List Apart: The Trouble With EM ’n EN (and Other Shady Characters)] "]

Some confusion exists within the Unicode standard of how to apply these under various spacing rules: [Korpela, Jukka (2000-2004) " [http://www.cs.tut.fi/~jkorpela/html/french.html HTML authoring in French] "]

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 !

Technology and approximations: input vs output

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. [Writers Block (1997) " [http://www.writersblock.ca/tips/monthtip/tipjun97.htm Writing Tips — Spacing (2)] "]

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 [see Emacs input notes, specifically regarding French-LaTeX-mode and the French-LaTeX-mode-hook variable (1991) [http://www.netlib.org/bibnet/tools/emacs/ltxmode/ltxmode.dif LaTeX Mode] ] ["French typography" in the Emacs LaTeX mode's included online-help [http://stuff.mit.edu/afs/sipb/project/sipb-old/lib/elisp/info/latex-mode.info-3 Info file: latex-mode.info] ] [as noted by Smith, Daniel J. (2005) " [http://jdanielsmith.spaces.live.com/Blog/cns!1pRjebUoVh0bNLSJvrecmAEg!339.entry Talking about One Space or Two Spaces After Punctuation -Rules of Desktop Publishing] "] from predefined typographic standards on input just as TeX infers them on output:
*non-breaking short spaces "(thin spaces)"
*non-breaking normal spaces "(thick spaces)"
*breaking normal spaces "(thick spaces)"
*breaking long spaces "(em spaces)"

Related spacing rules

Many Asian spacing rules for alphabetized printing distinguish between sentences which are closely related and those which are less closely related: an "intra"-concept inter-sentence space differs from an "inter"-concept inter-sentence space. The former is represented by a small vertically-(x-)centred circle ("◦"), the latter by a normal Western space. When printed, "inter"-concept inter-sentence spaces are often double-spaced.

Tibetan spacing rules are more complex, based on syllable-driven "phrases" rather than on words. Inter-word spaces are not used, but inter-syllable characters and inter-phrase spaces are used. When printed, Tibetan (and hence Bhutanese etc.) sentences are separated by a doubled inter-phrase space. [ [http://unicode.org/reports/tr2.html Unicode Technical Report #2: Tibetan Proposal] ] [Tashi Tsering (1997) "On Frequency Data of Tibetan Characters and Syllables" China Tibetology, No. 2]

ee also

*Kerning and Leading
*Punctuation in French

External links

* [http://michelf.com/weblog/2006/and-so-appeared-smartypants-typographer/ PHP SmartyPants Typographer] : PHP MarkDown extension inserting key French spacing non-breaking spaces into entered text
* A "Silesian Vocational and Technical" (1960) [http://www.archive.org/details/Typesett1960 training video for Linotype machines] , notable for its clarity regarding the technology's strengths and limitations, and the full explanation of the consequent spacing practice
*A List Apart: Sheerin, Peter K. (2001) " [http://www.alistapart.com/stories/emen/ The Trouble With EM ’n EN (and Other Shady Characters)] "
*Typophile forum discussion of " [http://www.typophile.com/node/3466 Double-spacing after periods] "
*Writers Block (1997) "Writing Tips — [http://www.writersblock.ca/tips/monthtip/tipmay97.htm Spacing (1)] " & " [http://www.writersblock.ca/tips/monthtip/tipjun97.htm Spacing (2)] "
*Discussion of double-spacing, French spacing, and English spacing, in the context of Tablet (untyped) input: " [http://hardware.mcse.ms/message202967.html Two spaces after period?] "
*Microsoft's " [http://www.microsoft.com/typography/developers/fdsspec/spaces.aspx Character design standards (5 of 10): Space Characters for Latin 1] "—notes on French typesetting in "Other space characters" section

References