In my recent book project with my photographer friend, Ellie, I learned a thing about en dashes and em dashes, as separate from hyphens. I brushed up on the topic by reading a discussion thread at painintheenglish.com.
“The hyphen is used to hyphenate compound words and between non-continuing numbers, e.g., phone numbers.
The en dash is used to “connect continuing, or inclusive, numbers — dates, time, or reference numbers.” [Chicago Manual of Style, sec. 5.115]
The em dash is used “to denote a sudden break in thought that causes an abrupt change in sentence structure.” [Chicago Manual of Style, sec. 5.106] When typing, it’s common to use two hyphens for an em dash. In HTML, you can also use the entity: “—”.”
I also learned that while in Word, an em dash is automatically generated by using two hypens, that you can make one manually on a PC by pressing Alt + 0151.
“An em dash is ASCI character 151, so Alt+0151 (on the numeric keypad) inserts it.
An en dash is character 150, so…
In Word on a PC, an en dash is CTRL + the numeric key pad minus sign, and an em dash is CTRL + Alt + numeric minus sign. This does not work in other programs.”
“On the Mac, if I type option + shift along with the dash key I get an m dash. If I type option and the dash key I get an n dash.”
Interesting, and useful for those of us who often have sudden breaks in our thought processes.