Dash
From Wikipedia, the free encyclopedia
- For other uses, see Dash (disambiguation).
- Note: This article contains special characters.
| Punctuation |
|---|
|
apostrophe ( ', ’ ) |
| Interword separation |
|
spaces ( ) ( ) ( ) |
| General typography |
|
ampersand ( & ) |
| Uncommon typography |
|
asterism ( ⁂ ) |
A dash is a punctuation mark. It is longer than a hyphen and is used differently.
Contents |
[edit] Common dashes
There are several forms of dash, of which the most common are:
| glyph | Unicode[1] | HTML[2] | HTML/XML[3] | |
|---|---|---|---|---|
| hyphen-minus | - | U+002D (45) | none | - or - |
| figure dash | ‒ | U+2012 (8210) | none | ‒ or ‒ |
| en dash | – | U+2013 (8211) | – |
– or – |
| em dash | — | U+2014 (8212) | — |
— or — |
| quotation dash | ― | U+2015 (8213) | none | ― or ― |
| swung dash | ⁓ | U+2053 (8275) | none | ⁓ or ⁓ |
- ^ Characters in Unicode are referenced in prose via the "U+" notation. The hexadecimal number after the "U+" is the character's Unicode code point. The decimal equivalent is shown in parentheses.
- ^ Specifically, the predefined character entity reference that can be used in an HTML document in place of a literal dash.
- ^ Specifically, the numeric character reference that can be used in an HTML or XML document in place of a literal dash.
[edit] Hyphen-minus
The hyphen-minus (-) was present in the ASCII and EBCDIC character encodings, and is typically used as a hyphen, a minus sign, and a dash in ASCII computer files. This compromise made sense in the days of monospacing typewriters and early computers and persists mainly because standard keyboards do not have the keys for the separate characters. 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.
[edit] 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. This does not indicate a range (en dash is used 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). HTML authors must use the numeric forms ‒ or ‒ to type it unless the file is in Unicode; there is no equivalent character 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.
[edit] En dash
The en dash (–), also known as the en rule, is one en in width: 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
- Notre Dame beat Miami 31–30
- New York–London flight
- Mother–daughter relationship
- The Supreme Court voted 5–4 to uphold the decision.
- The McCain–Feingold bill
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. For example, "a voltage of 50 to 100 V" rather than "a voltage of 50–100 V".
The en dash can be used instead of a hyphen in compound adjectives in which one part 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).
However, some authorities disagree with this usage.
The en dash is used instead of a hyphen in compound adjectives for which neither part of the adjective modifies the other. That is, when each is modifying the noun. This is common in science, when names compose an adjective as in Bose–Einstein condensate. Compare this with "award-winning novel" in which "award" modifies "winning" and together they modify "novel". Contrast "Franco-Prussian War", "Anglo-Saxon", etc., in which the first element does not strictly modify the second, but a hyphen is still normally used.
En dashes that are used instead of hyphens to connect words normally do not have spaces around them. An exception is when excluding them may cause confusion or look odd (e.g., 12 June – 3 July; contrast 12 June–3 July). However, when an actual en dash is unavailable, one may use a hyphen-minus with a single space on each side (" - ").
Like em dashes, en dashes can be used instead of colons, or pairs of commas that mark off a nested clause or phrase. They can also be used around parenthetical statements – such as this one – in place of the em dashes preferred by some publishers, particularly where short columns are used, since em dashes can look awkward at the end of a line. See En dash versus em dash, below. In these situations, en dashes must have 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 (--).
The en dash is sometimes used as a substitute for the minus sign, when the minus sign character is not available, since the en dash is usually the same width as a plus sign. For example, the original 8-bit Macintosh character set had an en dash, useful for minus sign, years before Unicode with a dedicated minus sign was available. The hyphen-minus is usually too narrow to make a typographically acceptable minus sign. The en dash cannot be used in programming languages for a minus, however, since the syntax usually requires a hyphen-minus; since programming languages are usually set in a fixed-pitch (monospaced) font face, the hyphen-minus looks acceptable there.
[edit] Em dash
The em dash (—), also known as the em rule, is defined as one em in width. An em is equivalent to the point size. Thus, in 9-point type an em is 9 points wide (as well as 9 points high) while the em of 24 point type is 24 points wide (and high), and so on. By definition, this is twice as wide as the en dash in any particular font.
Monospaced fonts such as Courier that mimic the look of a typewriter have the same width for all characters. Some of these fonts have em and en dashes which fill more or less of the monospaced width they have available. For example, “- – — −” will show as a hyphen, en dash, em dash, and minus in one's current monospace font. Traditionally typewriters had only a single hyphen glyph so it is common to use two monospace hyphens strung together--like this--to serve as an em dash.
The em dash indicates a sudden break in thought—a parenthetical statement like this one—or an open range (such as "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 or definitions, but that is a style guide issue: a colon should be used instead.
According to most American sources (e.g. the Chicago Manual) and to some British sources (e.g. the Oxford Guide to Style), an em dash should never be surrounded by spaces. The modern practice in many parts of the English-speaking world and in journalistic style is to separate the dash from its surrounding words when used parenthetically, by using spaces — or hair spaces (U+200A). Some writers prefer to use an en dash surrounded by spaces or hair spaces in lieu of the longer em dash. This "space, en dash, space" sequence is also the predominant style in German typography. See En dash versus em dash below.
When an actual em dash is unavailable, a double hyphen-minus ("--"), a triple hyphen-minus ("---"), or a single hyphen-minus with space on either side (" - ") are used. 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 (---).
[edit] 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.
Traditionally an em dash—like so—or spaced em dash — like so — has been used for a dash in running text. Some guides, including the Elements of Typographic Style, now recommend the more concise spaced en dash – like so – and argue that the length and visual magnitude of an em dash cater to grandiose Victorian era taste. However, some longstanding typographical guides such as The Chicago Manual of Style still recommend unspaced em dashes for this purpose. In practice, there is little consensus, and it is a matter of personal or house taste; the important thing is that usage should be consistent.
En dashes are often preferred to em dashes when text is set in narrow columns (as in newspapers and similar publications).
The en dash (always with spaces, in running text) or the spaced em dash has a certain technical advantage over the unspaced em dash: In most typesetting and most wordprocessing, the spacing 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 between which it falls. The effect can be uneven spacing in the text. Some argue that the spaced em dash risks introducing exaggerated spacing, in full justification.
[edit] Quotation dash
The quotation dash or horizontal bar (―) is used to introduce quoted text. This is standard method of printing dialogue in some languages (see the quotation dash section of the Quotation mark article for further details of how it is used).
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 character 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).
[edit] 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.
In LaTeX2ε, one can use the math mode command $\sim$.
[edit] 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 an open range, use an em dash (—)
- To make a compound adjective in which neither element modifies the other, use an en dash (–)
- For prefixing to a compound adjective that already has a hyphen (or a space) between elements, use an en dash (–)
- For parenthetical statements, use an em dash (—) with no surrounding space, or an en dash with surrounding space
- 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 (⁓)
[edit] 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 only be used as such when proper dashes are unavailable. Sometimes this is used in groups to indicate different types of dash.
- 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 used to indicate where a line may break, as in a compound word or between syllables.
- 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 lines found in some East Asian character sets. Typographically, they have the width of one CJK character cell, and follow the direction of the text (horizontal for horizontal text, vertical for columnar). They are used as dashes, and occasionally as emphatic variants of the katakana vowel extender mark.
In other languages:
- 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 Japanese chōon (ー), U+30FC, is used in Japanese to indicate a long vowel.
- The yī/ichi (一), U+4E00, means "one" in Chinese and Japanese.
[edit] 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 typically has support for many more characters, and is usually capable of rendering both the en and em dashes correctly—albeit sometimes with a little inconvenience for the user who has to input them. Some software, though, may operate in a more limited mode. Some text editors, for example, are restricted to working with a single 8-bit character encoding, and when unencodable characters are entered (e.g., by pasting from the clipboard), they are often blindly converted to question marks. Sometimes this happens to em and en dashes, even when the 8-bit encoding supports them, or when an alternative representation using hyphen-minuses would seem to be an option.
Any kind of dash can manifest directly in an HTML document, but HTML also allows them to be entered as character entity references. The entity names for the em dash and the en dash are mdash and ndash; therefore, they can be referenced in HTML as — and –. The equivalent numeric character 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 Australian, British, Canadian, German, Irish, Irish Extended, U.S., or U.S. Extended 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 ("-"). Mathematical minus is signified as "$-$".
Under recent versions of X11, you can obtain the em dash (—) by pressing the Compose key followed by - - - (triple hyphen-minus), and the en dash (–) can be obtained by pressing the Compose key followed by - - . (hyphen-minus, hyphen-minus, dot). In the absence of a Compose key, it can be emulated by remapping some other seldom used key.[1]
In Windows XP an en or em dash may be typed into most text areas by holding down the Alt key and pressing 0150 or 0151 respectively. The numbers must be typed on the numeric keypad with NumLock turned on.
With Microsoft Word's default settings (both Windows and Macintosh versions), an em dash is automatically produced by Autocorrect when two unspaced hyphens are entered between words ("word--word"). An en dash is automatically produced when one or two hyphens surrounded by spaces are entered: ("word - word") or ("word -- word"). This feature can be disabled by customising Autocorrect. 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. This will not work with the hyphen key on the main keyboard (usually between "0" and "="), which has completely different functions associated with it.
In professionally printed documents, the typographer sometimes adds a hair space, or, rarely, a full inter-word space, on either side of an em dash. In HTML it is possible to generate a hair space using the numeric character reference  , but current-generation web browsers are not uniformly supportive of this character, and may render it incorrectly.
[edit] External links
- Chicago Style Q&A - Hyphens, En Dashes, Em Dashes
- Peter K. Sheerin, The trouble with EM 'n EN
- Dashes and Hyphens
- Colons, Semicolons, and Em-dashes
- Commonly confused characters
- MediaWiki User's Guide to creating special characters
