Writing Tips

Dashes

From shortest to longest, the four kinds of dashes are the en dash, em dash, 2-em dash, and 3-em dash. (A hyphen is not a dash!) The most commonly used is the em dash; when the type of dash is not specified, an em dash is usually implied.

HTML, ASCII, typewriters, and certain fonts do not have a character for any of the dashes.

In the discussion that follows, an en dash is represented by one hyphen, an em dash by two hyphens, a 2-em dash by three hyphens, and a 3-em dash by four hyphens.

An en dash or em dash is not separated from adjacent words or punctuation by spaces. (At NIVA, with certain fonts, we use the advanced features of our software to very slightly increase the space surrounding a dash to produce a more pleasing appearance.) As demonstrated later, 2-em dashes and 3-em dashes are sometimes separated by spaces.

En dash

An en dash is used to indicate a range of values, but not when one of the limits of the range is a negative value. Note that the en dash replaces both "from" and "to".

• The city received 3-5 cm of rain last night.
• Equivalent: The city received from 3 to 5 cm of rain last night.
• Incorrect: The temperature that week was -3° —7°.

An en dash is also used to join two place names in certain contexts.

• Canada-U.S. trade relations
• The Ottawa-Montreal highway

An en dash may replace a hyphen when the hyphen must join a word to a hyphenated word and must replace the hyphen when a word or prefix is being joined to an open compound (phrase or proper noun consisting of more than one word). Some writers prefer to reword the sentence to avoid the construction.

• ex-father-in-law (ex + en dash + father + hyphen + in + hyphen + law),
• The pre-Vietnam War era

Em dash

Parenthetical expressions may be set off by brackets, parentheses, em dashes, or commas. Commas should be used for the least interruption in the sentence, followed by em dashes, parentheses, and brackets for progressively greater disconnection. A parenthetical phrase that contains commas must be set off by dashes or parentheses, not commas.

• Dave left later that day, around 2:30, for Toronto.
• Dave left later that day—around 2:30, at least—for Toronto.
• Dave left later that day—much later than expected—for Toronto.
• Dave left later that day for Toronto (before his brother arrived in Ottawa).

Em dashes are used to express a sudden break in thought.

• The former owner—it was a used car—was a mechanic.

A list of terms or a definition can be set off by dashes or parentheses, or preceded by a colon at the end of a sentence.

• Three people—George, Karen, and Mike—attended the meeting.
• Three people (George, Karen, and Mike) attended the meeting.
• Three people attended the meeting: George, Karen, and Mike.

An em dash is used to indicate undefined or unknown values in a table.

Any punctuation that normally would have been used in the sentence if the dashes and the material they enclose were not there should appear.

• Paul looked at his watch—the one that she gave him—; he was going to be late.
• (Paul looked at his watch; he was going to be late.)

An interrupted quotation is followed by an em dash. A comma should be used after a dash if needed to separate the quoted material from the rest of the sentence.

• "I never thought that—," he began to say.

If a parenthetical remark set off by dashes requires an exclamation point or question mark, the exclamation point or question mark can precede the second dash.

• She was going to tell him—or was she?—that it was over between them.

To avoid confusion, use only one or two dashes in a sentence.

Two-em dash

A 2-em dash is used to indicate missing letters. If the missing letters appear at the start or end of a word, the normal word space precedes or follows the dash.

• The manager ha—- the report.

Three-em dash

A 3-em dash marks a word that was omitted or that is to be added later. A normal word space appears on either side.

• The team leaves for —— next week.

A 3-em dash is also used in a bibliography when an author's name is repeated.

• Johns, Evan. 1965. An Industrial History of Ontario. Toronto: Fieldhouse Press.
• ——. 1971. Canada's Railroads. Toronto: Fieldhouse Press.