Q. My editor and I disagree about comma placement in this sentence. I added the comma, but he says it’s not necessary. Your opinion, please? “The screen design includes functional elements like text-entry boxes and list boxes, and stylistic elements like graphics and multimedia.” Thanks!

A. Your editor objects because it’s a “rule” not to put a comma between two elements making up a compound object. The comma is needed in your sentence, however, because your two elements are themselves compound. Without the comma, the reader is left to navigate some pretty rickety syntax: X includes A like B and C and D like E and F. Readability trumps the rule, so the comma should stay.