The Chicago Manual of Style is what Inkd uses for fiction, so we’ll discuss common issues here. Your professional editor should have access to the most up-to-date version.
Writers, however, rely on editors. Publishers have a part in the ellipsis concern as well.
In section 12.68 of the CMOS, it starts by stating:
A Chicago-style ellipsis consists of three spaced periods . . . like that.
However, despite the ruling, publishers make the final choice between the three spaced periods above and the horizonatl ellipsis character … because:
To prevent these periods (. . .) from breaking at the end of a line, nonbreaking spaces must be applied before and after the middle period; additionally, a nonbreaking space is required between the third period and any comma, semicolon, question mark, or exclamation point that follows . . . , like that. (This must be done prior to publication and is usually the responsibility of the publisher or typesetter.) Some publishers instead use the horizontal ellipsis character (…), defined for Unicode as U+2026. This character, which has the advantage of not breaking over a line, may also be preferred by some authors when they are preparing their manuscripts (alternatively, three unspaced periods, which will also stay together, may be used, provided only one type of ellipsis appears throughout a document).
For a writer’s perspective, just be consistent. You can ask a publisher what they prefer, but if you are consistent, they can make a global replacement. The nonbreaking spaces between the Chicago-style ellipsis should be the editor / publisher’s concern if they are using it. Some software makes the decision for them.
However, along with consistency, there are distinct rulings about spacing around the ellipsis that need to be followed.
A space should be used before and after an unspaced ellipsis … like that, except when the ellipsis is followed by a comma or other mark of punctuation …, like that. (For spaced period ellipsis): additionally, a nonbreaking space is required between the third period and any comma, semicolon, question mark, or exclamation point that follows . . . , like that.
Consistency and spaces, with rules for punctuation.