The use of a single character for both hyphen and minus was a compromise made in the early days of fixed-width typewriters and computer displays. However, in proper typesetting and graphic design, there are distinct characters for hyphens, dashes, and the minus sign. Usage of the hyphen-minus nonetheless persists in many contexts, as it is well-known, easy to enter on keyboards, and in the same location in all common character sets.
On typewriters, it was conventional to use a pair of hyphens to represent an em dash, and this convention is still sometimes used in computer text.
The hyphen-minus is often used to represent an en dash, which may be used to indicate:
- Ranges, such as a time range of "2000–2004".
- Connection or direction, as in "The Los Angeles–London flight".
- Compound adjectives, when there is already a hyphenated compound present, as in "He submitted his manuscript to an e-book–only publisher".[unreliable source]
The en dash is normally longer (the width of a letter "n") than a hyphen, though in a fixed-pitch or typewriter font there is no difference. The hyphen connects closely, the en dash less closely, while the em dash (the width of a letter "m") separates.
The minus sign is nominally the same width as the plus sign, longer than a hyphen; an en dash, being closer to the right length, is sometimes preferred over the hyphen-minus to represent a minus sign when the Unicode minus is not available.
- Jukka K. Korpela (2006). Unicode explained. O'Reilly. p. 382. ISBN 978-0-596-10121-3.
- Fischer, Eric. "The Evolution of Character Codes, 1874-1968" (PDF). Retrieved 2016-11-16.
- Ritchie, Dennis (c. 1975). "C Reference Manual" (PDF). Retrieved 2016-12-07.
- "Haskell 2010 Language Report" (PDF). Retrieved 2016-12-07.
- Penn, Jordan (2016). "En dash". The Punctuation Guide. self-published. Retrieved 13 January 2018.
- "Hyphens, En Dashes, Em Dashes". The Chicago Manual of Style Online. Retrieved 25 January 2017.
- Hardesty, Ray E. (2010). Technical and Business Writing for Working Professionals. Xlibris. p. 90. ISBN 9781456819408.[self-published source]