Q. Should there be a space on either side of an ellipsis in the middle of a line when using the Unicode ellipsis rather than three spaced periods? Example: Should there be a … space … like this? I’ve read CMOS 13.50, which says that authors can use the ellipsis character in their manuscripts instead of spaced ellipses, “usually with a space on either side.” But several authors disagree with me as an editor. Most authors insist on no…spaces…like this. Several have them like this… with a space on the right side only, before the clause continues. Thank you for your help!

A. Any of the approaches you mention can be valid when used consistently. But when you’re using an ellipsis character (or unspaced periods, which are similar) rather than three spaced periods in a manuscript that’s otherwise in Chicago style, put a space on either side of the ellipsis except immediately before another mark of punctuation:

This ellipsis … is in the middle of a sentence.
This one is at the end. … Note the space after the period.
This ellipsis is preceded by a comma, … with similar spacing.
What do you mean? … More of the same.
But when punctuation follows …, close it up to the ellipsis.
Is that wise …? We think so.

Do this whether you’re using the ellipsis to stand in for an omission (as in quoted text) or to signal a faltering or hesitation (as in fictional narrative or dialogue). But note that in fiction, periods and commas aren’t typically used next to an ellipsis (see this recent Q&A for more details).

An editor following Chicago style would then replace each instance of “…” with “. . .”—making sure to include a nonbreaking space before and after the middle period and between the last period and any comma or other mark of punctuation (except for a parenthesis or quotation mark) that immediately follows the third period.

Usage outside Chicago varies, as you suggest. AP, for example, recommends unspaced periods used similarly to the examples above. BuzzFeed’s advice depends on whether the ellipsis indicates a pause or an omission. Whatever you end up doing, apply it consistently (and according to a consistent logic).