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THERE’S A MULTIPLICITY of punctuation marks that look quite similar: -, –, —, and ―. These are, respectively, the hyphen, the en dash, the em dash, and the horizontal bar. And don’t forget − (the arithmetical minus sign), – (the hyphen-minus), and ⁓ (the swung dash).
We’d need a sharp eye, a micrometer, or a bit of Unicode to differentiate some of these. On the other hand, in less than precise typography, several have been known to masquerade for each other.
Here are some tidbits on the en dash and em dash. Sources are Keith Houston’s Shady Characters: The Secret Life of Punctuation, Symbols, and Other Typographical Marks, together with my usual Internet sleuthing.
En and Em Etymologies. These two punctuations get their names from their sizes: An en dash, –, is said to be as wide as the letter n; an em dash, —, the letter m. I hedge here, because some font styles differ in this.
Also, the em is the same length as the font’s height, the latter usually measured in “points.” That is, in 12-point type, an em dash is 12 points in length.
In general, the en dash is longer than a hyphen, -. An em dash is usually twice the length of an en dash. On my keyboard, a double hit on the hyphen gives —, which sure looks like an em dash to me. And Option + hyphen gives –, an en dash.
En Dash Use. According to Wikipedia, the en dash has three main uses: 1. to connect symmetric items, 2. to serve as a hyphen in certain compounds, and 3. to act as a sentence interrupter.
In this first use, for example, the Boston Patriots recently beat the Los Angeles Rams 13–3. England’s King Charles II reigned 1660-1685. An average new car costs $35,000–$36,000.
The second use reminds me of an R&T convention in the old days: For example, the term “high–performance tire inflation pressures,” would have had an en in “high–performance” and none in the “tire inflation” part, which is called grammatically an “open compound.”
The en dash’s third use as “sentence interrupter” has it substitute for a pair of commas, parentheses, or to indicate a rhetorical phrase: In fact, it overlaps with the em dash in this regard – but not in The Chicago Manual of Style. (This is an en dash in the preceding sentence, though Chicago would disagree on such usage.)
Em Dash Use. According to Wikipedia, “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.”
For example, an em dash may replace a comma or colon—as in this sentence. Or it may signal an interruption—but then again…
Em dashes are also useful in identifying sources of quotes: “Out, damn’d spot!”—Lady Macbeth, Macbeth, Act 5, scene 1.
I believe she was talking about blood, not punctuation marks. ds
© Dennis Simanaitis, SimanaitisSays.com, 2019