Despite what I think I know about English grammar, I continually encounter tricky grammatical situations. Most of the time I find the answer in my hard copy of The Chicago Manual of Style (CMS). As you can see from the picture of my CMS, a number of sticky notes mark sections I’ve looked up. In the perfect world, they’d look a heck of a lot more neat; however, many times when I was looking rules up, I was on a time crunch.
I have no idea which item I looked up when, but for at least couple I have a memory relating to the why of looking it up.
Section 2.80 “Manuscript cleanup checklist,” number nine on the checklist: “Change underlines to italics,” unless the underline is a transcribed underscore (p. 93). If this is the case—the underline needs to be there—leave an explanatory note for the publisher.
Prior to buying the manual, and likely when I was editing one of my manuscripts, I learned from someone somewhere on an Internet search that underlines are no longer necessary to indicate italicization. However, my fiction and nonfiction college professors, during the 2019-20 school year, underlined what I’d italicized in short works I’d submitted to them. I’m pretty sure I recycled my sticky note from the “em dash” section and stuck it here while proving to myself that my professors were the one’s who were incorrect.
FYI: Number nine under 2.80 contains a “see also,” section 6.2. “Punctuation and italics” instructs us to keep punctuation marks in the same font “as the main or surrounding text,” unless they’re actually part of the italicized title. The section goes on to elaborate and provide examples (364-5).