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En dash or hyphen - this time quoting from the OSM

Posted by Anders on November 23, 2003

Hello friends
Below I give you, as promised, the quote from the Oxford Style Manual. Upon reading it again, I can see where they are going with this. If the rule is now no longer mind-blowing to me, it is at least arresting. Literally. It interrupts your writing. Cost-benefit analysis - let me correct myself: cost–benefit analysis (to replace the hyphen with the en dash) - remains a case in point. True, the meaning is cost-to-benefit or benefit-to-cost analysis; but whereas the Ali-Foreman match may just as well be called the Foreman-Ali match, this is not so with cost-benefit analysis: benefit-cost analysis is simply, if not unidiomatic, certainly markedly less current. Google show the former to be about 12 times as widespread as the latter. (Cost-benefit analysis: 367,000 hits; benefit-cost analysis: 30,300 hits). If some users or companies have invested different meanings into these two expressions, they are even less interchangeable than the factor 12 indicates. And if so, it’s so much the worse for the rule of the en rule.

Use the en rule closed up to express the meaning of to or and between words of equal importance. In these cases the words can be reversed in order without altering the meaning. The hyphen must be used when the first element cannot stand on its own.
Dover–Calais crossing
on–off switch
editor–author relationship
Permian–Carboniferous boundary
Ali–Foreman match
dose–response curve
cost–benefit analysis
wave–particle duality