In my previous post about parenthetical phrases, I talked about commas, parentheses, and em dashes. This week, I’ll discuss the once-common practice of using two hyphens instead of an em dash.
Typewriters
Typewriters don’t have em dash keys, so typists used two hyphens to visually approximate an em dash.
This practice declined in popularity along with the typewriter itself. However, the double hyphen is still used in some situations where a true em dash is not available (for example, in ASCII-encoded text).
Monospaced Fonts
Most fonts are “proportional fonts,” meaning that some characters are wider than others. For example, a capital letter W is usually wider than a lowercase letter l.
In proportional fonts, em dashes, en dashes, and hyphens can are easily distinguished by their varying widths. An em dash (—) is as wide as the letter M, an en dash (–) is as wide as the letter N, and a hyphen (-) is about half as wide as an en dash.
In monospaced fonts, such as Courier New and Lucida Console, every character is the same width. Although these fonts do have an em dash character, it’s hard to tell it apart from the en dash and the hyphen.
Although I couldn’t find an applicable rule in any of our style guides, if you’re using a monospaced font (for example, if you’re writing a screenplay), I think you would be forgiven for using two hyphens to help the reader’s understanding.
Use an Em Dash the Rest of the Time
Whenever you’re using a proportional font (which is most of the time), forget the double hyphen—use an em dash instead.
In Microsoft® Word and Outlook, if you type two hyphens (without spaces before or after), they’re automatically replaced with an em dash.
Alternatively, you can hold down the Alt and Ctrl keys, and then press – on the number pad.
Ben Ritter | Technical Editor | Symitar®
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