Q. Should “time travel” be hyphenated as a verb? CMOS 5.25 says it’s okay to use nouns as verbs, but there are no two-word examples. “Time travel” isn’t even in M-W!

A. According to our hyphenation guide at CMOS 7.89 (sec. 2, “phrases, verbal”), a verb phrase that doesn’t appear in the dictionary may be left open. Each of the examples in CMOS also appears in Merriam-Webster (where it is either closed, hyphenated, or open): babysit, handcraft, air-condition, fast-talk, strong-arm, sucker punch. Because “time travel” does not, it may be left open. (By the way, if you figure out how to travel through time, or time travel, and end up crossing paths with the Time Traveler from the classic novel by H. G. Wells, please say hello from us.)

Q. Hi all! I hope everyone is staying safe. I have a quick question. Should it be “What will my teacher say about my never returning to class?” or “What will my teacher say about me never returning to class?” Citations will help. I struggle with this frequently. Thank you so much! Take care.

A. Either one is acceptable, though “my” has traditionally been considered to be the more correct choice in sentences like yours. See CMOS 7.28 for an explanation and examples. For a grammar-based explanation, see CMOS 5.114.

The choice of “my” depends on reading “returning” as a gerund, which is a verb’s present participle acting as a noun. A noun can be the object of a preposition, and if “returning” is the object of the preposition “about,” then “my” is correct because a possessive pronoun is required before a noun. (For example, one would write about “my dog,” not “me dog.”)

But “me” is common in such constructions; it’s also grammatically defensible. If you read “me” as the object of the preposition “about,” then “returning” would function as a present participle that modifies the pronoun “me”—as in, “They saw me returning to class the other day.”

In sum, traditionalists may balk at “me” and the so-called fused participle that it creates, but “me” will have its supporters—and in some cases it’s the better choice.

Q. “ZIP Code” is trademarked and essentially an invention by the USPS. They created it with a capitalized “C.” Why do you insist that this “C” is rendered in lowercase?

A. You are right that the United States Postal Service writes “ZIP Code” with a capital C—and ZIP in all caps. You’re also right about us. Though CMOS doesn’t specifically rule on how to capitalize the term, it has rendered it as “zip code” (all lowercase) since it first appeared in the Manual in 1982 (in the 13th ed.). Our editors at that time would have been conforming such passing mentions to the main entries in Webster’s New Collegiate Dictionary (8th ed., Merriam-Webster, 1973). The eighth Collegiate had “zip code n, often cap Z&I&P” (those are ampersands between the letters Z and I and P)—the same as in the current dictionary from Merriam-Webster. (Compare the entry for “Kleenex,” which is listed with a capital K and noted as a trademark.)

Merriam-Webster and CMOS aren’t the only influential resources that don’t fully conform to Postal Service usage. The 2020–2022 edition of the Associated Press Stylebook says to write “all-caps ZIP for Zone Improvement Plan, but always lowercase the word code.” But don’t despair. We are filing your question with the many other suggestions from our readers for future editions of CMOS. Though “zip code” may remain our preferred style for general references to the numeric locator that in the US has become practically synonymous with “neighborhood,” we’ll make a note to acknowledge the trademarked styling as well.

Q. CMOS does not mention uses of the en dash for conflict or connection, as in “the liberal–conservative debate” or “the Radical–Unionist coalition.” Should it be inferred that CMOS opposes such uses?

A. CMOS would never oppose the consistent application of sound editorial logic, but we try to tailor our recommendations to serve both editors and readers. En dashes bump up against the limits of this goal. Editors tend to love them, but readers who haven’t been editors or proofreaders may not even notice them. If Chicago has resisted adding the sense of “between” or “and” to the more common use of the en dash as “to,” that’s the primary reason (see CMOS 6.80).

Because we do see the value of using an en dash in a phrase like “Ali–Frazier fight” or “Epstein–Barr virus.” Those dashes signal that you’re not referring to a fight or a virus that involves somebody with a hyphenated last name. And we wouldn’t want a “liberal–conservative debate” to be read as a debate about conservatives who are liberal, as a hyphen might imply. But if readers won’t get this from those en dashes (most of us—even those of us who can discern an en dash from a hyphen—will rely on context to figure out the intended meaning), is it worth an editor’s trouble to apply them?

True, we already take the time to convert hyphens to en dashes in number ranges, mostly because we know that “99–100” is a hair more legible than “99-100.” But pattern matching makes this easy to do. And we usually replace a hyphen with an en dash in “pre–Civil War” and the like—in the possibly vain hope that readers are more likely to see at a glance that it’s not a war that’s “pre-Civil.”

But we would need to be confident that more readers have become en dash literate before adding to our existing recommendations. If that ever happens, Chicago’s recommended uses for the character also known as Unicode 2013 may end up expanding.

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!

A. Technically, yes: two commas would still be considered correct. But the problem with that first comma—and the reason we discourage it—is that unlike dashes, semicolons, and opening parentheses, which are forward looking, commas tend to be backward looking. For example,

The committee, that is, its more influential members, wanted to drop the matter.

Does the phrase “that is” in the example above belong with the words that come before it, or does it belong to the words that follow? A stronger mark solves this potential for a momentary misreading by providing more structure to the sentence:

The committee (that is, its more influential members) wanted to drop the matter.

Another solution is to simply omit the second comma:

The committee, that is its more influential members, wanted to drop the matter.

That last approach is fine for casual prose, but formal prose usually calls for the more structured punctuation choices recommended in CMOS.

Q. Hi, I see that CMOS 8.36 discusses kinship names and when to capitalize versus when to lowercase. I’m wondering about a term like “sir” or “ma’am” used in direct address: “Yes, ma’am” or “Yes, Ma’am”? I think probably the former, but what do you recommend? Thank you.

A. You’re right to prefer lowercase. Terms like “sir” and “ma’am” are almost never used literally as titles these days. Instead they’re more often like common nouns or pronouns, as in “Hello, stranger,” or “Hey, you.” So unless you are transcribing a conversation with Sir Paul McCartney or Dame Judi Dench (two modern celebrities on whom titles have been conferred; see CMOS 8.32), write “Yes, sir” and “Yes, ma’am.” Compare “Greetings, Doctor.” In that case, “Doctor” is a proper noun standing in for a person’s name in the form “Dr. Surname.” But these distinctions can be fuzzy; when in doubt—or to convey a less formal tone—use lowercase.

Q. How do you cite a photograph of a piece of art that is in a book chapter with two authors and the book has several editors? Do you need all of the creators—photographer, artist, authors, and editors? Thank you!

A. We get a lot of questions like yours. They generally go something like this: “How do I cite a picture / drawing / marginal annotation / coffee mug stain / whatever that I found in a book?” The answer is generally the same: describe the object in your text; then cite the book accordingly.

So in your text you would describe the artwork as needed—for example, what it is and who created it and when; assuming you’ve done that, there’s usually no need to give additional details in a note. Nor would you need to name the photographer as credited in the book, a redundant move that would amount to citing another source’s cited sources.

Then you would simply cite the book as a whole and provide a page number where the image may be found. If the chapter itself is relevant to the artwork or to your discussion, you will want to cite the book in terms of the chapter. Here’s the format you would use:

1. Author One and Author Two, “Title of Chapter,” in Title of Book, ed. Editor One, Editor Two, and Editor Three (City: Publisher, 2020), 147.

If, however, the artwork is central to your discussion—or you’re a student and your instructor requires it—you may want to cite the artwork itself. In that case, it would be best to track down its location in a gallery or online and to confirm the relevant details there rather than relying on the secondary source information in the book (though the book should give you a head start on finding the artwork and the information about it that you will need). Examples may be found at CMOS 14.235.