dash

dash

1. There are, in formal printing at least, two types of dash: the en-rule (–) and the em-rule ( —). An en-rule is twice the length of a hyphen, and an em-rule is twice the length of an en-rule. Most word-processing programs are able to distinguish the two lengths of rule, but in ordinary writing no distinction is usually made (and many people are not even aware of one).

2. The shorter en-rule has two principal uses: (1) to separate a range of dates, as in pages 34–6 and the 1939–45 war, and (2) to join the names of joint authors and suchlike, as in the Temple–Hardcastle project and Lloyd–Jones, 1939 (as a citation; Lloyd-Jones, with a hyphen, would be a single double-barrelled name).

3. The longer em-rule is the more familiar in everyday use, and corresponds to what most people understand by the term dash. Its principal uses are: (1) a single dash used to introduce an explanation or expansion of what comes before it

• (It is a kind of irony of history that I should write about the French Revolution in the very country where it has had the least impact —I mean England, of course —Encounter, 1990)

and (2) a pair of dashes used to indicate asides and parentheses, forming a more distinct break than commas would

• (Helen has only seen her father once in her adult life and —until her flight from Grassdale —her brother is a virtual stranger to her —J. Sutherland, 1996).

The use of a dash to stand for a coarse word (e.g. f–) in reported speech is much less common than it used to be, because public acceptance of these words spelt out is that much greater.