Hyphens, En Dashes, Em Dashes

Q. A question arose in my proofreading class about the phrase “rock and roll.” Merriam-Webster suggests that when it is used as a noun, no hyphens are required, and when used as an adjective, hyphens are preferred. Our question was whether we should choose one or the other and stick with it through the entire document or alternate between hyphenating and not hyphenating depending upon usage.

A. Good question! The dictionary can’t make this clear, but a good style guide can: you should consistently hyphenate the adjective phrase and consistently leave the noun open. Your proofreading class would benefit from a look at the hyphenation table at CMOS 7.89.