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Dashes are used as internal punctuation marks for linkage and clarity of expression. In APS Style, they are used sparingly.
Use the em dash sparingly to indicate an abrupt break in thought, especially in long, complex sentences. Em dashes should not be overused; use commas or parentheses, as appropriate, if the author overuses the em dash.
In APS Style, the em dash is used after the title line of the abstract.If used by the author in quoted material (references, quotes), leave it unchanged.
En dashes are used to indicate a range, including page ranges in the reference list; however, when the words "from" or "between" introduce a range, an en dash must not be used.
good
from 1 to 6 mg/ml
between 10 and 20 mM
bad
from 1–6 mg/ml
between 10–20 mM
En dashes must not be used when the second value in the range is a negative number.
good
–4 to –6°C
bad
–4– –6°C
To create an em dash in a manuscript, use three hyphens (---).
To create an en dash in a manuscript, use two hyphens (--).
A hyphen between two numerals will be automatically set as an en dash by the printer; e.g., the hyphen in "226-232" will appear as an en dash in proof. If you want to "force" a hyphen between two numerals, e.g., in an extended zip code or phone number, use the «hyphen» code.
Bethesda, Maryland 20814«hyphen»3991
When creating the mathematical minus symbol or a negative numeral, do not use an en dash; use the «minus» code instead.
5 «minus» 2 = 3.
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last edited 07/23/03