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Em dash)
A dash is a punctuation mark, and is not to be confused with the hyphen, which has quite different uses.
Common dashes
Several forms of dashes exist, of which the most common are:
| |
glyph
|
Unicode
|
HTML entity
|
| hyphen-minus |
- |
U+002D (45) |
- (ASCII)
|
| figure dash |
‒ |
U+2012 (8210) |
none |
| en dash |
– |
U+2013 (8211) |
– |
| em dash |
— |
U+2014 (8212) |
— |
| quotation dash |
― |
U+2015 (8213) |
none |
| swung dash |
⁓ |
U+2053 (8275) |
none |
Hyphen-minus
Main article: Hyphen
The hyphen-minus (-) is the ASCII character typically used as a hyphen, a minus sign, and a dash in ASCII computer files. Strictly speaking, it is not a dash at all; thus, careful typesetting (including with modern computer applications, such as word processors and HTML) usually uses the following proper dashes instead.
Figure dash
The figure dash (‒) is so named because it is the same width as a digit, at least in fonts with digits of equal width.
The figure dash is used when a dash must be used within numbers, for example with telephone numbers: 634‒5789. Note that this does not indicate a range (use an en dash for that), or function as the minus sign (which has its own glyph).
The figure dash is often unavailable; in this case, one may use a hyphen-minus instead. In Unicode, the figure dash is U+2012 (decimal 8210). In HTML, you must use the numeric forms ‒ or ‒ to type it; there is no equivalent HTML entity. In TeX, the standard fonts have no figure dash; however, the digits normally all have the same width as the en dash, so an en dash can be substituted in TeX.
En dash
The en dash (–) is one en in width. By definition, this is by exactly half the width of an em dash.
The en dash is used to indicate a closed range, or a connection between two things of almost any kind: numbers, people, places, etc. For example:
- June–July 1967
- 1:00–2:00 p.m.
- For ages 3–5
- pp. 38–55
- New York–London flight
The Guide for the Use of the International System of Units (SI) recommends that the word "to" be used instead of an en dash when a number range might be misconstrued as subtraction, such as a range of units.
The en dash can also be used as a hyphen in a compound adjective, one part of which consists of two words or a hyphenated word:
- pre–World War II period
- anti–New Zealand sentiment
- high-priority–high-pressure tasks (tasks which are both high-priority and high-pressure).
The en dash is also used, with a single space on each side, instead of a colon, and around parenthetical statements – like this one – in place of the more common em dash. See En dash versus Em dash below.
Except when used parenthetically or instead of a colon, an en dash does not have spaces around it. However, when an actual en dash is unavailable, one may use a hyphen-minus with a single space on each side (" - "). In Unicode, the en dash is U+2013 (decimal 8211). In HTML, one may use the numeric forms – or –; there is also an HTML entity –. In TeX, the en dash may normally (depending on the font) be input as a double hyphen-minus (--).
Em dash
The em dash (—) is defined as one em in width. By definition, this is twice as wide as the en dash in any particular font.
The em dash indicates a sudden break in thought—a parenthetical statement like this one—or an open range (like "John Doe, 1987—"). The em dash is used in much the way a colon or set of parentheses is used: it can show an abrupt change in thought or be used where a period is too strong and a comma too weak. Em dashes are sometimes used in lists of definitions, but this is not considered correct usage: a colon should be used instead.
In North American usage—and also in old British usage—an em dash is never surrounded by spaces. In contrast, the modern practice in Europe and Australasia — and, indeed, many other parts of the English-speaking world — is to separate the dash from its surrounding words when used parenthetically, by using spaces — or hair spaces (U+200A). Some writers eschew the use of the em dash – instead, they replace it with the shorter en dash – which is then also surrounded by spaces or hair spaces; this "space, en dash, space" sequence is also the predominant style in German typography.
When an actual em dash is unavailable, a double hyphen-minus ("--") can be used in American English. However, this has never been accepted in other variants of English, such as Commonwealth English; instead, a single hyphen-minus is used with space on either side (" - "), just as for the en dash. In Unicode, the em dash is U+2014 (decimal 8212). In HTML, one may use the numeric forms — or —; there is also the HTML entity —. In TeX, the em dash may normally be input as a triple hyphen-minus (---).
En dash versus Em dash
The en dash is half the width of the em dash. The width of the en dash was originally the width of the typeset letter "N", while the width of the em dash was the width of "M"; hence the names.
Some people prefer to use an en dash instead of an em dash for parenthetical statements, and also where a dash is to be used to replace a colon. A spaced en dash is commonly used for this purpose in British publications, whereas in the USA the tendency is to use the unspaced em dash.
The spaced en dash has a certain technical advantage over the (unspaced) em dash. In most typesetting and most wordprocessing, the space between words is expected to be variable, so there can be full justification. Alone among punctuation that marks pauses or logical relations in text, the (unspaced) em dash disables this for the words it falls between. The effect can be uneven spacing in the text. (The spaced em dash risks introducing exaggerated spacing, in full justification.)
However, it is sometimes argued that using an en dash here can lead to confusion, on the grounds that the dashes have different semantic roles.
Quotation dash
The quotation dash or horizontal bar (―) is used to introduce quoted text. This is standard method of printing dialogue in some languages, such as Spanish and (at least to some extent) Italian.
If the quotation dash is unavailable, then the em dash can be used instead. In Unicode, the quotation dash is U+2015 (decimal 8213). In HTML, it can be input only with the numeric form, ― or ―; there is no equivalent HTML entity. But since browser support for it is nearly non-existent and Unicode itself equates use, for web pages one generally uses the em dash. There is no support in the standard TeX fonts, but one can use \hbox{---}\kern-.5em--- instead (or just use an em dash).
Swung dash
The swung dash (⁓) resembles a lengthened tilde, and is used to separate alternatives. In dictionaries, it is frequently used to stand in for the defined term in example text.
The swung dash in Unicode is U+2053 (decimal 8275). In HTML, it can be input only with the numeric form, ⁓ or ⁓; there is no equivalent HTML entity.
Summary
To summarize the above:
- To write a number with a dash in it, use the figure dash (‒)
- For a closed range, use an en dash (–)
- For a compound adjective with a space, use an en dash (–)
- For an open range, use an em dash (—)
- For parenthetical statements, use an em dash (—)
- To introduce a quotation, use a quotation dash (―)
- To separate alternatives, use a swung dash (⁓)
- To replace a defined term in an example of usage within a definition, use a swung dash (⁓)
Other dash-like characters
The are several characters which resemble dashes but have different meanings and uses. These include:
- The hyphen-minus (-), Unicode U+002D, is the standard ASCII hyphen. It looks like a dash, but should never be used as such outside of ASCII.
- The tilde (~), U+007E, is a diacritic mark.
- The underscore (_), U+005F, is either a diacritic mark, or a character replacing a standard space.
- The macron (¯), U+00AF, is another diacritic mark.
- The soft hyphen ( ), U+00AD, is a hyphen which should only appear at a line break.
- The Armenian hyphen (֊), U+058A, is a hyphen from the Armenian alphabet.
- The Mongolian todo hyphen (᠆), U+1806, is a hyphen from the Mongolian alphabet.
- The hyphen (‐), U+2010, is a character which, unlike the ASCII hyphen, always represents a hyphen.
- The hyphen bullet (⁃), U+2043, is a short horizontal line used as a list bullet.
- The minus sign (−), U+2212, is an arithmetic operator used in mathematics to represent subtraction or negative numbers.
- The wave dash (〜), U+301C, and the wavy dash (〰), U+3030, are wavy horizontal lines found in some East Asian character sets, and included in Unicode for backward-compatibility.
Rendering dashes on computers
Typewriters and computers have traditionally had only a limited character set, often having no key with which to produce a dash. In consequence, it became common to substitute the nearest incorrect punctuation mark or symbol. Em dashes are often represented by a pair of spaces surrounding a single hyphen-minus (typical British usage) or by a pair of spaces surrounding two hyphen-minuses (mostly in the United States).
Modern computer software, however, typically has a much expanded character set and is usually perfectly capable of rendering both the en and em dashes correctly—albeit with a little inconvenience.
The HTML entity names for the em dash and the en dash are — and –. The equivalent HTML numeric character entity references are — and –. Nearly all web browsers and operating systems used today are capable of rendering the numeric form, and almost as many correctly display the named form.
In Unicode, the figure dash, en dash, em dash, quotation dash, and swung dash correspond to characters U+2012, U+2013, U+2014, U+2015, and U+2053, respectively.
In Mac OS using the U.S. or U.K. keyboard layout, an en dash can be obtained by typing option-hyphen, while an em dash can be typed with option-shift-hyphen.
In TeX, an em dash is typed as three hyphens ("---"), an en dash as two hyphens ("--"), and a hyphen-minus as one hyphen ("-").
In Microsoft Word for Windows and Macintosh, an em dash will be produced by Autocorrect when two hyphens are entered between words ("word--word"). An en dash is produced by two hyphens surrounded by spaces ("word -- word"). Other dashes, spaces, and special characters are possible, found through Tools -> Customize... -> Keyboard... -> Common Symbols. Unassigned symbols (such as the true minus sign) can be assigned keyboard shortcuts through Insert -> Symbol... -> (select desired symbol) -> Shortcut key...
In Word for Windows, an em dash can be typed with ctrl+alt+numeric hyphen (on the numeric keypad, usually in the top right corner), and an en dash can be typed with ctrl+numeric hyphen. Note that it will not work with the hyphen key on the main keyboard (usually between "0" and "="), which has completely different functions associated with these commands.
In professionally printed documents, the typographer sometimes adds a hair space on either side of an em dash (a refinement that is not practicable in HTML given the limitations of current-generation web browsers) or even a full space, though this last is uncommon.
See also
- Wikipedia:Manual of Style (dashes)
External links
Last updated: 06-01-2005 15:36:28
