Q. Can you clarify when commas should be used with an “or” phrase? For example, should it be “Table salt, also known as sodium chloride or NaCl” or “Table salt, also known as sodium chloride, or NaCl”?

Q. According to CMOS 6.51, “Expressions of the type that is are traditionally followed by a comma. They are best preceded by an em dash or a semicolon rather than a comma, or the entire phrase they introduce may be enclosed in parentheses or em dashes.” My question is this: Would it still be acceptable to use a comma in such expressions rather than the em dash or parentheses? Thank you!

Q. When an expression like “11 minutes, 52 seconds” occurs in the middle of a sentence (as in “We finished 11 minutes, 52 seconds ahead of the next car”), is a second comma required? If not, why?

Q. I don’t understand why the following example in the serial comma section (CMOS 6.19) is not considered a comma splice: “Paul put the kettle on, Don fetched the teapot, and I made tea.”

Q. I’ve gone through your section on commas numerous times, yet I can’t seem to find whether a comma would be used in the following instance: “You can be very helpful to your mother or father, or to a person you think of as a parent.”

Q. Regarding the placement of a comma after “of course,” I’d always treated “of course” used emphatically differently from “of course” used as an aside. With the emergence of better grammar checkers being utilized with an assumption of accuracy, I now see more of this: “Can I come over?” “Of course, you can.” Is this actually correct? I’ve been unsuccessful in finding a conclusive answer. Some sources say you always put a comma after “of course.” Others say it’s up to the author. Since it seems that the placement of a comma can change the meaning, I’d hoped for something a bit more definitive than “You do you, boo.”

Q. In previous Q&A entries, you’ve said to include a comma after “Inc.” or “Ltd.” if a comma precedes it: “The office of ABC, Inc., was located downtown.” I could understand the reason for this if “Inc.” were replaced by a generic description: “The office of ABC, an incorporated company, was located downtown.” But since “Inc.” is a capitalized part of a formal, proper name, wouldn’t this be analogous to the example in CMOS 6.17 about titles of works, in which a title containing a comma doesn’t need to be followed by a comma (“Look Homeward, Angel was not the working title of Wolfe’s manuscript”)? If not, what’s the distinction?

Q. Hello! I have a comma question. Which is the preferred punctuation: Amherst, Massachusetts’ Emily Dickinson . . . OR Amherst, Massachusetts’, Emily Dickinson . . . ? Recasting the sentence is not a useful option because there is a longish list of names and places: Long Branch, New Jersey’s Bruce Springsteen and Lachine, Quebec’s Saul Bellow and . . . Thanks.

Q. Is it correct to use commas before and after “myself,” “himself,” “herself,” “itself,” etc. in cases like “I, myself, wouldn’t wear that dress”?

Q. Why does a comma follow Washington, DC, in running text?