Dash

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The dash is a punctuation mark that is similar in appearance to U+002D - hyphen-minus and U+2212 - minus sign, but differs from these symbols in both length and height. The most common versions of the dash are the en dash (-), equal to half the height of the font; the em dash (--), twice as long as the en dash; and the horizontal bar (-), whose length varies across typefaces.

Historically, the names of en dash and em dash were loosely related to the width of a lower-case n and upper-case M, respectively, in commonly used typefaces.

Usage varies both within English and in other languages, but the usual convention in printed English text is as follows:

• An em dash denotes a break in a sentence or to set off parenthetical statements:

  Glitter, felt, yarn, and buttons--his kitchen looked as if a clown had exploded.
  A flock of sparrows--some of them juveniles--alighted and sang.

• The en dash but not the em dash indicates spans or differentiation, where it may be considered to replace "and" or "to" (but not "to" in the phrase "from ... to ..."):

  The French and Indian War (1754-1763) was fought in western Pennsylvania and along the present US-Canada border (Edwards, pp. 81-101).

• The em dash or the horizontal bar, but not the en dash is used to set off the sources of quotes:

  Seven social sins: politics without principles, wealth without work, pleasure without conscience, knowledge without character, commerce without morality, science without humanity, and worship without sacrifice.--Mahatma Gandhi

• The horizontal bar (or the em dash, but not the en dash) introduces quoted text at line start.

Video Dash

Common dashes and Unicode characters

There are several forms of dash, of which the most common are:

Less common are the two-em dash (?) and three-em dash (?), both added to Unicode with version 6.1 as U+2E3A and U+2E3B.

Maps Dash

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. This is true of most fonts, not only monospaced fonts.

The figure dash is used within numbers (e.g. phone number 555-0199), especially in columns for maintaining alignment. Its meaning is the same as a hyphen, as represented by the hyphen-minus glyph; by contrast, the en dash is more appropriately used to indicate a range of values; the minus sign also has a separate 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 when using standard TeX fonts. In XeLaTeX, one could use \char"2012 (Linux Libertine font has the figure dash glyph).

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En dash

The en dash, en rule, or nut (-) is traditionally half the width of an em dash. In modern fonts, the length of the en dash is not standardized, and the en dash is often more than half the width of the em dash. The widths of en and em dashes have also been specified as being equal to those of the upper-case letters N and M respectively, and at other times to the widths of the lower-case letters.

Usage

The two main uses of the en dash are to connect symmetric items, such as the two ends of a range or two competitors or alternatives, and as a substitute for a hyphen in a compound when one of the connected items is more complex than a single word.

Ranges of values

The en dash is commonly used to indicate a closed range of values--a range with clearly defined and finite upper and lower boundaries--roughly signifying what might otherwise be communicated by the word "through". This may include ranges such as those between dates, times, or numbers. Various style guides restrict this range indication style to only parenthetical or tabular matter, requiring "to" or "through" in running text. Preference for hyphen vs. en dash in ranges varies. For example, the APA style (named after the American Psychological Association) uses an en dash in ranges, but the AMA style (named after the American Medical Association) uses a hyphen:

Various style guides (including the Guide for the Use of the International System of Units (SI) and the AMA Manual of Style) recommend that when a number range might be misconstrued as subtraction, the word "to" should be used instead of an en dash. For example, "a voltage of 50 V to 100 V" is preferable to using "a voltage of 50-100 V". Relatedly, in ranges that include negative numbers, "to" is used to avoid ambiguity or awkwardness (for example, "temperatures ranged from -18 °C to -34 °C", or alternately, -18 °C...-34 °C). It is also considered poor style (best avoided) to use the en dash in place of the words to or and in phrases that follow the forms from X to Y and between X and Y.

Relationships and connections

The en dash can also be used to contrast values, or illustrate a relationship between two things. Examples of this usage include:

• Australia beat American Samoa 31-0.
• Radical-Unionist coalition
• Boston-Hartford route
• New York-London flight (however, it may be seen that New York to London flight is more appropriate because New York is a single name composed of two valid words; with a dash the phrase is ambiguous and could mean either Flight from New York to London or New flight from York to London)
• Mother-daughter relationship
• The Supreme Court voted 5-4 to uphold the decision.
• The McCain-Feingold bill

Among writers who use en dashes in these contexts, a distinction is often made between "simple" attributive compounds (written with a hyphen) and other subtypes (written with an en dash); at least one authority considers name pairs, where the paired elements carry equal weight, as in the Taft-Hartley Act to be "simple", while others consider an en dash appropriate in instances such as this to represent the parallel relationship, as in the McCain-Feingold bill or Bose-Einstein statistics. However, there is a difference between something named for a parallel/coordinate relationship between two people (for example, Bose and Einstein) and something named for a single person who had a compound surname, which may be written with a hyphen or a space but not an en dash (for example, the Lennard-Jones potential [hyphen] is named after one person (Mr. John Lennard-Jones), as are Bence Jones proteins and Hughlings Jackson syndrome [space]). Copyeditors use dictionaries (general, medical, biographical, and geographical) to confirm the eponymity (and thus the styling) for specific terms, given that no one can know them all offhand.

The preference for an en dash instead of a hyphen in these coordinate/relationship/connection types of terms is a matter of style preference, not inherent orthographic "correctness"; both are equally "correct", and each is the preferred style in some style guides. For example, the American Heritage Dictionary of the English Language, the AMA Manual of Style, and Dorland's medical reference works use hyphens, not en dashes, in coordinate terms (such as blood-brain barrier), in eponyms (such as Cheyne-Stokes respiration, Kaplan-Meier method), and so on.

Attributive compounds

In English, the en dash is usually used instead of a hyphen in compound (phrasal) attributives in which one or both elements is itself a compound, especially when the compound element is an open compound, meaning it is not itself hyphenated. This manner of usage may include such examples as:

• The hospital-nursing home connection (the connection between the hospital and the nursing home, not a home connection between the hospital and nursing)
• A nursing home-home care policy (a policy about the nursing home and home care)
• Pre-Civil War era
• Pulitzer Prize-winning novel
• The non-San Francisco part of the world
• The post-World War II era
  • (Compare post-war era, which, if not fully compounded (postwar), takes a hyphen, not an en dash. The difference is that war is not an open compound whereas World War II is.)
• Trans-New Guinea languages
• The ex-prime minister
• a long-focal length camera
• water ice-based bedrock
• The pro-conscription-anti-conscription debate
• Public-school-private-school rivalries

The disambiguating value of the en dash in these patterns was illustrated by Strunk and White in The Elements of Style with the following example: When Chattanooga News and Chattanooga Free Press merged, the joint company was inaptly named Chattanooga News-Free Press (using a hyphen), which could be interpreted as meaning that their newspapers were news-free.

An exception to the use of en dashes is usually made when prefixing an already-hyphenated compound; an en dash is generally avoided as a distraction in this case. Examples of this include:

• non-English-speaking air traffic controllers
• semi-labor-intensive industries
• Proto-Indo-European language
• The post-MS-DOS era
• non-government-owned corporations

An en dash can be retained to avoid ambiguity, but whether any ambiguity is plausible is a judgment call. AMA style retains the en dashes in the following examples, but one could argue that some perverseness may be needed to construe the hyphens-only alternative as ambiguous:

• non-self-governing
• non-English-language journals
• non-group-specific blood
• non-Q-wave myocardial infarction
• non-brain-injured subjects

Differing recommendations

As discussed above, the en dash is sometimes recommended instead of a hyphen in compound adjectives where neither part of the adjective modifies the other--that is, when each modifies the noun, as in love-hate relationship.

The Chicago Manual of Style (CMOS), however, limits the use of the en dash to two main purposes:

• First, use it to indicate ranges of time, money, or other amounts, or in certain other cases where it replaces the word to.
• Second, use it in place of a hyphen in a compound adjective when one of the elements of the adjective is an open compound, or when two or more of its elements are compounds, open or hyphenated.

That is, the CMOS favors hyphens in instances where some other guides suggest en dashes, the 16th edition explaining that "Chicago's sense of the en dash does not extend to between", to rule out its use in "US-Canadian relations".

In these two uses, en dashes normally do not have spaces around them. An exception is made when avoiding spaces may cause confusion or look odd. For example, compare "12 June - 3 July" with "12 June-3 July".

Parenthetic and other uses at the sentence level

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 expressions - 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.

Itemization mark

Either the en dash or the em dash may be used as a bullet at the start of each item in a bulleted list. (This is a matter of graphic design rather than orthography.)

Typography

Spacing

In most uses of en dashes, such as when used in indicating ranges, they are closed up to the joined words. It is only when en dashes take the role of em dashes - for example, in setting off parenthetical statements such as this one - that they take spaces around them. For more on the choice of em versus en in this context, see En dash versus em dash.

Encoding and substitution

When an en dash is unavailable in a particular character encoding environment--as in the ASCII character set--there are some conventional substitutions. Often two hyphens are the substitute.

In Unicode, the en dash is U+2013 (decimal 8211). In HTML, one may use the numeric forms – or –; there is also the HTML entity –.

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 the 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. However, the en dash cannot be used for a minus sign in programming languages because the syntax usually requires a hyphen-minus.

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Em dash

The em dash, em rule, or mutton (--) is longer than an en dash. The character is called an em dash because it is one em wide, a length that varies depending on the font size. One em is the same length as the font's height (which is typically measured in points). So in 9-point type, an em dash is 9 points wide, while in 24-point type the em dash is 24 points wide. By comparison, the en dash, with its 1-en width, is in most fonts either a half-em wide or the width of an "n".

Usage

The em dash is used in several ways: primarily in places where a set of parentheses or a colon might otherwise be used, it can show an abrupt change in thought or be used where a full stop (period) is too strong and a comma too weak. Em dashes are also used to set off summaries or definitions. Common uses and definitions are cited below with examples.

Colon-like use

Simple equivalence (or near-equivalence) of colon and em dash

• Three alkali metals are the usual substituents: sodium, potassium, and lithium.
• Three alkali metals are the usual substituents--sodium, potassium, and lithium.

Inversion of the function of a colon

• These are the colors of the flag: red, white, and blue.
• Red, white, and blue--these are the colors of the flag.

Parentheses-like use

Simple equivalence (or near-equivalence) of paired parenthetical marks

• Compare parentheses with em dashes:
  • Three alkali metals (sodium, potassium, and lithium) are the usual substituents.
  • Three alkali metals--sodium, potassium, and lithium--are the usual substituents.
• Compare commas, em dashes and parentheses (respectively) when no internal commas intervene:
  • The food, which was delicious, reminded me of home.
  • The food--which was delicious--reminded me of home.
  • The food (which was delicious) reminded me of home.

Subtle differences in punctuation

It may indicate an interpolation stronger than that demarcated by parentheses, as in the following from Nicholson Baker's The Mezzanine. (The degree of difference is subjective.)

• "At that age I once stabbed my best friend, Fred, with a pair of pinking shears in the base of the neck, enraged because he had been given the comprehensive sixty-four-crayon Crayola box--including the gold and silver crayons--and would not let me look closely at the box to see how Crayola had stabilized the built-in crayon sharpener under the tiers of crayons."

Interruption of a speaker

Interruption by someone else

In this use, it is sometimes doubled:

• "But I'm trying to explain that I--"
  "I'm aware of your mitigating circumstances, but your negative attitude was excessive."

In a related use, it may visually indicate the shift between speakers when they overlap in speech. For example, the em dash is used this way in Joseph Heller's Catch-22:

• He was Cain, Ulysses, the Flying Dutchman; he was Lot in Sodom, Deirdre of the Sorrows, Sweeney in the nightingales among trees. He was the miracle ingredient Z-147. He was--
  "Crazy!" Clevinger interrupted, shrieking. "That's what you are! Crazy!"
  "--immense. I'm a real, slam-bang, honest-to-goodness, three-fisted humdinger. I'm a bona fide supraman."

Self-interruption

• Simple revision of a statement as one's thoughts evolve on the fly:
  • "I believe I shall--no, I'm going to do it."
• Contemplative or emotional trailing off (usually in dialogue or in first person narrative):
  • "I sense something; a presence I've not felt since--" in Star Wars Episode IV: A New Hope.
  • "Get out or else--"

Either an ellipsis or an em dash can indicate aposiopesis, the rhetorical device by which a sentence is stopped short not because of interruption, but because the speaker is too emotional or pensive to continue. Because the ellipsis is the more common choice, an em dash for this purpose may be ambiguous in expository text, as many readers would assume interruption, although it may be used to indicate great emotion in dramatic monologue.

• Long pause:
  • In Early Modern English texts and afterward, em dashes have been used to add long pauses (as noted by Joseph Robertson's 1785 An Essay On Punctuation):

Lord Cardinal! if thou think'st on heaven's bliss,
Hold up thy hand, make signal of that hope.--
He dies, and makes no sigh!

Quotation

Quotation mark-like use

This is a quotation dash. It may be distinct from an em dash in its coding (see Horizontal bar). It may be used to indicate turns in a dialog, in which case each dash starts a paragraph. It replaces other quotation marks, and was preferred by authors such as James Joyce:

-Oh saints above! Miss Douce said, sighed above her jumping rose. I wished I hadn't laughed so much. I feel all wet

-Oh Miss Douce! Miss Kennedy protested. You horrid thing!

Attribution of quote source

• Inline quotes:
  • A penny saved is a penny earned. -- Benjamin Franklin
• Block quotes:

Redaction

An em dash may be used to indicate omitted letters in a word redacted to an initial or single letter or to fillet a word, by leaving the start and end letters whilst replacing the middle letters with a dash or dashes (for the purposes of censorship or simply data anonymization). In this use, it is sometimes doubled.

• It was alleged that D---- had been threatened with blackmail.

Three em dashes might be used to indicate a completely missing word.

Itemization mark

Either the en dash or the em dash may be used as a bullet at the start of each item in a bulleted list, but a plain hyphen is more commonly used (and even mandatory in formats like Markdown).

Repetition

Three em dashes one after another can be used in a footnote, endnote, or another form of bibliographic entry to indicate repetition of the same author's name as that of the previous work, which is similar to the use of ibid.

Typographic details

Spacing and substitution

According to most American sources (such as The Chicago Manual of Style) and some British sources (such as The Oxford Guide to Style), an em dash should always be set closed, meaning it should not be surrounded by spaces. But the practice in some parts of the English-speaking world, including the style recommended by The New York Times Manual of Style and Usage for printed newspapers and the AP Stylebook, sets it open, separating it from its surrounding words by using spaces or hair spaces (U+200A) when it is being used parenthetically. The AP Stylebook rejects the use of the open em dash to set off introductory items in lists. Some writers, finding the em dash unappealingly long, prefer to use an open-set en dash. This "space, en dash, space" sequence is also the predominant style in German and French typography. (See En dash versus em dash below.)

On a practical note, when the em dash is set closed (not surrounded by spaces), it makes highlighting in ebooks difficult, as two words are often treated as conjoined.

In Canada, The Canadian Style: A Guide to Writing and Editing, The Oxford Canadian A to Z of Grammar, Spelling & Punctuation: Guide to Canadian English Usage (2nd ed.), Editing Canadian English, and the Canadian Oxford Dictionary all specify that an em dash should be set closed when used between words, a word and numeral, or two numerals.

The Australian government's Style Manual for Authors, Editors and Printers (6th ed.), also specifies that em dashes inserted between words, a word and numeral, or two numerals, should be set closed. A section on the 2-em rule (?) also explains that the 2-em can be used to mark an abrupt break in direct or reported speech, but a space is used before the 2-em if a complete word is missing, while no space is used if part of a word exists before the sudden break. Two examples of this are as follows (properly typeset 2-em and 3-em dashes should appear as a single dash, but they may show on this page as several em dashes with spaces in between):

• I distinctly heard him say, "Go away or I'll ----".
• It was alleged that D---- had been threatened with blackmail.

Monospaced fonts that mimic the look of a typewriter have the same width for all characters. Some of these fonts have em and en dashes that more or less fill the monospaced width they have available. For example, the sequence "hyphen, en dash, em dash, minus" shows as "- - -- -" in a monospace font.

Approximating the em dash with two or three hyphens

When an em dash is unavailable in a particular character encoding environment--as in the ASCII character set--it has usually been approximated as a double (--) or triple (---) hyphen-minus. The two-hyphen em dash proxy is perhaps more common, being a widespread convention in the typewriting era. (It is still described for hard copy manuscript preparation in the Chicago Manual of Style as of the 16th edition, although the manual conveys that typewritten manuscript and copyediting on paper are now dated practices). The three-hyphen em dash proxy was popular with various publishers because the sequence of one, two, or three hyphens could then correspond to the hyphen, en dash, and em dash, respectively.

Because early comic book letterers were not aware of the typographic convention of replacing a typewritten double hyphen with an em dash, the double hyphen became traditional in American comics. This practice has continued despite the development of computer lettering.

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En dash versus em dash

The en dash is wider than the hyphen but not as wide as the em dash. An em width is defined as the point size of the currently used font, since the M character is not always the width of the point size. In running text, various dash conventions are employed: an em dash--like so--or a spaced em dash -- like so -- or a spaced en dash - like so - can be seen in contemporary publications.

Various style guides and national varieties of languages prescribe different guidance on dashes. Dashes have been cited as being treated differently in the US and the UK, with the former preferring the use of an em dash with no additional spacing and the latter preferring a spaced en dash. As examples of the US style, The Chicago Manual of Style and The Publication Manual of the American Psychological Association recommend unspaced em dashes. Style guides outside the US are more variable. For example, The Elements of Typographic Style by Canadian typographer Robert Bringhurst recommends the spaced en dash - like so - and argues that the length and visual magnitude of an em dash "belongs to the padded and corseted aesthetic of Victorian typography". In the United Kingdom, the spaced en dash is the house style for certain major publishers, including the Penguin Group, the Cambridge University Press, and Routledge. However, this convention is not universal. The Oxford Guide to Style (2002, section 5.10.10) acknowledges that the spaced en dash is used by "other British publishers" but states that the Oxford University Press, like "most US publishers", uses the unspaced em dash.

The en dash - always with spaces in running text when, as discussed in this section, indicating a parenthesis or pause - and the spaced em dash both have a certain technical advantage over the unspaced em dash. Most typesetting and word processing expects word spacing to vary to support 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. This can cause uneven spacing in the text, but can be mitigated by the use of thin spaces, hair spaces, or even zero-width spaces on the sides of the em dash. This provides the appearance of an unspaced em dash, but allows the words and dashes to break between lines. The spaced em dash risks introducing excessive separation of words. In full justification, the adjacent spaces may be stretched, and the separation of words further exaggerated. En dashes may also be preferred to em dashes when text is set in narrow columns, such as in newspapers and similar publications, since the en dash is smaller. In such cases, its use is based purely on space considerations and is not necessarily related to other typographical concerns.

On the other hand, a spaced en dash may be ambiguous when it is also used for ranges, for example, in dates or between geographical locations with internal spaces.

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Horizontal bar

U+2015 - Horizontal bar, also known as a quotation dash, is used to introduce quoted text. This is the standard method of printing dialogue in some languages. The em dash is equally suitable if the quotation dash is unavailable or is contrary to the house style being used.

There is no support in the standard TeX fonts, but one can use \hbox{---}\kern-.5em--- instead, or just use an em dash.

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Swung dash

U+2053 ? swung dash resembles a lengthened tilde, and is used to separate alternatives or approximates. In dictionaries, it is frequently used to stand in for the term being defined. A dictionary entry providing an example for the term henceforth might employ the swung dash as follows:

henceforth (adv.) from this time forth; from now on; "? she will be known as Mrs. Wales"

There are several similar, related characters:

• U+007E ~ TILDE (see below)
• U+02DC ~ SMALL TILDE (see below)
• U+223C ~ Tilde operator, used in mathematics. Ends not curved as much regular tilde. In TeX and LaTeX, this character can be expressed using the math mode command $\sim$.
• U+301C ? Wave dash, used in East Asian typography for a variety of purposes, including Japanese punctuation.
• U+FF5E ~ Fullwidth tilde is a compatibility character for a wide tilde used in East Asian typography.

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Similar Unicode characters

Similar Unicode characters used in specific writing systems

• U+058A ? Armenian hyphen
• U+05BE ? Hebrew maqaf
• U+1400 ? Canadian syllabics hyphen
• U+1428 ? Canadian syllabics final short horizontal stroke
• U+1806 ? MONGOLIAN TODO SOFT HYPHEN is a hyphen from the Mongolian Todo alphabet.
• U+1B78 ? Balinese musical symbol left-hand open pang
• U+2E0F ? paragraphos is an Ancient Greek textual symbol, usually displayed by a long low line.
• U+2E17 ? DOUBLE OBLIQUE HYPHEN is used in ancient Near-Eastern linguistics.
• U+2E1A ? HYPHEN WITH DIAERESIS is used mostly in German dictionaries and indicates umlaut of the stem vowel of a plural form.
• U+2E40 ? DOUBLE HYPHEN is used in the transcription of old German manuscripts.
• U+30A0 = KATAKANA-HIRAGANA DOUBLE HYPHEN
• U+3161 ? HANGUL LETTER EU or U+1173 ? HANGUL JUNGSEONG EU are Hangul letters used in Korean to denote the sound [?].
• U+301C ? WAVE DASH and U+3030 ? wavy dash are wavy lines found in some East Asian character sets. Typographically, they have the width of one CJK character cell (fullwidth form), and follow the direction of the text, being horizontal for horizontal text, and vertical for columnar. They are used as dashes, and occasionally as emphatic variants of the katakana vowel extender mark.
• U+30FC ? KATAKANA-HIRAGANA PROLONGED SOUND MARK, the Japanese ch?onpu, is used in Japanese to indicate a long vowel.
• U+4E00 ? CJK UNIFIED IDEOGRAPH-4E00, the Chinese character for "one", is used in various East Asian languages.
• U+A4FE ? Lisu punctuation comma looks like a sequence of a hyphen and a full stop.
• U+FE31 ? PRESENTATION FORM FOR VERTICAL EM DASH is a compatibility character for a vertical em dash used in East Asian typography.
• U+FE32 ? PRESENTATION FORM FOR VERTICAL EN DASH is a compatibility character for a vertical en dash used in East Asian typography.
• U+FE58 ? SMALL EM DASH is a compatibility character for a small em dash used in East Asian typography.
• U+FF5E ~ Fullwidth tilde is a compatibility character for a wide tilde used in East Asian typography.
• U+FE63 - SMALL HYPHEN-MINUS is a compatibility character for a small hyphen-minus used in East Asian typography.
• U+FF0D - FULLWIDTH HYPHEN-MINUS is a compatibility character for a wide hyphen-minus used in East Asian typography.
• U+10110 ? Aegean number ten
• U+1104B ? Brahmi punctuation line
• U+11052 ? Brahmi number one
• U+110BE ? Kaithi section mark
• U+1D360 ? Counting rod unit digit one

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In other languages

In many languages, such as Polish, the em dash is used as an opening quotation mark. There is no matching closing quotation mark; typically a new paragraph will be started, introduced by a dash, for each turn in the dialog.

Corpus studies indicate that em dashes are more commonly used in Russian than in English. In Russian, the em dash is used for the present copula (meaning "am"/"is"/"are"), which is unpronounced in spoken Russian.

In French, em or en dashes can be used as parentheses (brackets), but the use of a second dash as a closing parenthesis is optional. When a closing dash is not used the sentence is ended with a period (full-stop) as usual. Dashes are, however, much less common than parentheses.

In Spanish, em dashes can be used to mark off parenthetical phrases. Unlike in English, the em dashes are spaced like brackets, i.e., there is a space between main sentence and dash, but not between parenthetical phrase and dash.

Una bandada de gorriones --algunos de ellos jóvenes-- se posó y cantó.

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Rendering dashes on computers

Typewriters and early computers have traditionally had only a limited character set, often having no key that produces a dash. In consequence, it became common to substitute the nearest available punctuation mark or symbol. Em dashes are often represented in British usage by a single hyphen-minus surrounded by spaces, or in American usage by two hyphen-minuses surrounded by spaces.

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 an inconvenient input method. 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--for example 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 is an option.

Any kind of dash can be used directly in an HTML document, but HTML also lets them be entered using character references. The em dash and the en dash are special in that they can be written using character entity references as — and –, respectively. Mozilla Thunderbird provides for entry of HTML sequences including — and – using its Insert drop-down menu.

• In UNIX and GNU/Linux, there are various methods of producing these dashes:
  • For em dashes, one may use the compose/multi key followed by three presses of the hyphen character. For en dashes, one may press the compose key followed by two hyphens and a period. Also, other keys may be remapped to create dashes.
  • In X Window System, the em dash may be entered by pressing the compose key and three hyphens.
  • In GTK+ applications (including outside Unix/Linux, such as in The GIMP), all dashes and other Unicode characters can be produced with ? Shift+ctrl+u, which displays a u, then enter a Unicode number for the appropriate dash, and then press the space bar or the enter/return key. For example, ? Shift+ctrl+u and 2013 creates an en dash; the number 2014 is for creating an em dash.
• For the en dash, LaTeX has the macro (\textendash).
• In macOS using the Australian, British, Canadian, Finnish, French, German, Irish, Irish Extended, Italian, Pro Italian, Russian, US, US Extended, or Welsh keyboard layout, an en dash can be obtained by typing ? Opt+-, while an em dash can be typed with ? Opt+? Shift+-.
• In TeX, an em dash (--) is typed as three hyphen-minuses (---) and an en dash (-) as two hyphen-minuses (--). Mathematical minus (-) is signified as $-$ or \(-\).
• On Plan 9 systems, an en or em dash may be entered by pressing the Compose key (usually left Alt), followed by typing en or em respectively.
• In Microsoft Windows, with Num lock enabled for numeric keypads or on laptop keyboards, an en- or em-dash may be typed into most text areas by using their respective Alt code by holding down the Alt key and pressing either 0150 for the en dash, or Alt+0151 for the em dash. Num Lock must be enabled for Alt code combinations to work. In addition, the Character Map utility included with Windows can be used to copy and paste en and em dash characters into most applications; if an Alt code exists for a character, a user can click on it in the character map, and see the corresponding Alt code in the app's status bar.
• In Microsoft Word running on a computer whose keyboard has a numeric keypad, an em dash can be typed with Ctrl+Alt+- (on the numeric keypad, with the numeric hyphen usually in the top-right corner), and an en dash can be typed with Ctrl+-. This does not work with the hyphen key on the main keyboard (between "0" and "=" with a US or UK layout), which has completely different functions. With Microsoft Word's default settings, in both Windows and Macintosh versions, an em dash symbol, which is not always a true em dash from the font, is automatically produced by Autocorrect when two unspaced hyphens are entered between words (as in "word--word"). An en dash, which again, is not always a true en dash from the font, is automatically produced when one or two hyphens surrounded by spaces are entered: ("word - word") or ("word -- word"). This feature can be disabled by customizing Autocorrect.

To determine if the true en- or em-dash from the font are being used, rather than a cross-referenced character from the Symbol font, one can copy and paste a sample of the dash into Word or WordPad followed by Alt+X. The hexadecimal Unicode number will appear, revealing whether the character is a true en- or em-dash (Unicode 2013 or 2014). Using the true dash is important, if one needs to share documents with other users in other applications or operating systems.

The true en- and em-dash, along with other dashes, spaces, and special characters, such as the true minus sign, can be inserted through the Insert menu without the use of the numeric keypad, which some keyboard layouts do not always provide. These symbols can also be assigned keyboard shortcuts through this menu.

src: generalassemb.ly

See also

• Leiden Conventions - rules to indicate conditions in texts (usage of "[-- -- --]")
• Signature dashes - signature delimiter in emails (usage of "-- " in a single line)

src: upload.wikimedia.org

Notes

src: cdn.shopify.com

References

External links

• Wiktionary list of English phrases with em dash
• Wiktionary list of English phrases with en dash
• Dashes and Hyphens
• Commonly confused characters

Source of article : Wikipedia