See Hyphens for the uses of the shortest form of a dash.
En dash
The en dash or en rule (–) is about the width of the letter n. An en dash is used:
- for parenthetical information (i.e. instead of commas, round brackets or an em dash) – the en dash is shorter than the em dash, and the space on either side allows the text to reflow more easily to suit screens of different sizes:
The results of the experiment – which were circulated to all laboratories – were very interesting.
Several countries have policies that address this issue – for example, India, New Zealand and the United Kingdom.
- to indicate a number range (but not if the range is preceded by from or between)
10–20 kg but from 10 to 20 kg or between 10 and 20 kg
pages 650–657
to indicate a date range (but not if the range is preceded by from or between)
1995–96 2012–13 [do not repeat ‘19’ or ‘20’ in the second element, but, for ranges that cross centuries, use the form 1995–2001]
When a span of dates includes 2 different months, a spaced en dash is sometimes used to indicate the range, but avoid this if possible by using the word to to show the range:
1 July 2013 – 25 August 2013 1 July 2013 to 25 August 2013
- to indicate an equal relationship between 2 words; in this case, the en dash means ‘to’ or ‘and’
Sydney–Canberra rail link
Murray–Darling Basin
Burdekin–Fitzroy River
gas–liquid chromatography
cost–benefit analysis
- to connect names in terms credited to more than 1 author (or inventor, etc)
Creutzfeldt–Jacob disease
Michaelis–Menten constant
- to represent chemical bonds (see Chemical compounds)
- as a minus symbol if a mathematical minus symbol is not available or if the symbol is needed infrequently (see Negative numbers)
- for a list within a list (see Lists).
Word processing tip
How to insert an en dash
In Windows (e.g. Microsoft Word), use Ctrl+- on the numerical keypad; use Alt+0150 on the numerical keypad; or insert from the symbol set (special characters). On a Mac, use Option+-. Word can also be set up to convert 2 hyphens (--) to an en dash (–) using the autocorrect options.
Em dash
The em dash or em rule (—) is about the width of the letter m. An unspaced em dash can be used to indicate parenthetical information (i.e. as a substitute for commas, round brackets or en dashes):
The results of the experiment—which were circulated to all laboratories—were very interesting.
Many style guides (including this one) recommend a spaced en dash rather than an em dash, so check with your organisation or journal. Spaced en dashes also tend to be more common in digital publishing (see En dash).
Word processing tip
How to insert an em dash
In Windows (e.g. Microsoft Word), use Ctrl+Alt+- on the numerical keypad; use Alt+0151 on the numerical keypad; or insert from the symbol set (special characters). On a Mac, use Option+Shift+-.
Slash
A slash (/) is used:
- to replace per in expressions of rate or concentration
120 km/h 4 t/ha 3 g/mL
- to replace for in expressions of rate or concentration
wt/wt wt/vol
- in mathematical expressions to indicate that one term is divided by another (see Mathematics and statistics)
1/4 y = 3.5/(a + b)
- in the expression and/or; however, this is awkward and ambiguous, and should be avoided if possible. In most cases where a writer has used and/or, it is possible to use and with no loss of meaning:
Environmental reporting can occur at the local, regional, state and territory and/or national levels.
becomes
Environmental reporting can occur at the local, regional, state and territory, and national levels.
- in URLs to mark the end of the protocol (usually 2 slashes are used)
http:// https://
- in URLs to indicate a directory
- to close HTML tags
/a [closing tag of a hyperlink] /font [closing tag of a font element] /p [closing tag of a paragraph element]
Do not use a slash to indicate a ratio or spans of years:
1:3 not 1/3
2010–12 not 2010/12
Slashes are sometimes used to indicate a financial year. An en dash is recommended instead:
2003–04 financial year not 2003/04 financial year
Avoid using a slash to combine terms, such as administrator/supervisor or general practitioner/specialist. Readers have to work hard to decide what the slash means (and or or), and this can sometimes be critical to the meaning. Instead, give the alternatives in full, recasting the sentence, if necessary:
The administrator/supervisor should be informed.
becomes
The administrator and supervisor should be informed.
or
The administrator or supervisor should be informed.
or
It may be necessary to consult either the administrator or the supervisor, or, in some circumstances, both.
The phase I/phase II trials showed …
becomes
The phase I and phase II trials both showed …
Sometimes a slash is used (incorrectly) to replace an en dash:
The doctor/patient relationship
means
The doctor–patient relationship
but is better written as
The relationship between the patient and the doctor
Similarly:
cost–benefit ratio not cost/benefit ratio
dose–response study not dose/response study
To refer to the plural as an alternative to the singular, use parentheses around the s, rather than using a slash:
representative(s) not representative/s
Ellipsis
An ellipsis (…) is used in quotations to indicate an omission of text:
Dr Williams stated, ‘The samples were analysed using a range of methods … no significant differences were found’.
Insert a space each side of the ellipsis if it occurs in the middle of a sentence. If the ellipsis occurs at the end of a sentence, insert a space before it and do not follow it with a full stop.
Word processing tip
How to insert an ellipsis
The shortcut for an ellipsis in Microsoft Word is Ctrl+Alt+. (on a PC) and Option+; (on a Mac).