cover of Chicago Manual of Style

Three CHICAGO MANUAL OF STYLE  Rules … and Their Exceptions

Anyone who has used Chicago Manual of Style, or any style guide for that matter, will know that sometimes the rules seem arbitrary or contradictory and full of exceptions. Here are three often confused rules and their many exceptions.

  1. Number rules: When to use numerals versus when to spell out a number.
  2. The Chicago Manual of Style has an entire section dedicated to the treatment of numbers! Twenty-eight pages of rules in the 17th edition hardcover. One of which I just used in the last sentence, CMOS 9.5: “When a number begins a sentence, it is always spelled out.”

    Chicago’s number rules follow a standard pattern for most usages. Numbers one through one hundred are always spelled out (unless used as part of a percentage, date, or time), and those higher than one hundred, and up through the hundred thousands, find whole numbers spelled out—forty-seven thousand or three hundred—with everything else up to one hundred in numeral form—423, 11,354, etc.

    But the ultimate exception to the rule comes in Chicago 9.7: Consistency and flexibility.

    Where many numbers occur within a paragraph or series of paragraphs, maintain consistency in the immediate context. If according to a given rule you must use numerals for one of the numbers in a given category, use them for all in that category.

    Chicago has very specific rules about when to use numerals and when to spell out numbers, here Chicago tells you to forget what you have been taught in the previous seven sections, but to default to the lowest common denominator, aka, if you must use numerals for one, use them for all. Consistency is key.

  3. Possessives: Plural possessives and names ending in s
  4. Possessives are a constant source of confusion for writers and editors alike. Take what is a common area for errors and add in the extra confusion of plural possessives as well as proper nouns ending in s, and you have a formula for exceptions and non-uniform treatment across style guides. The Chicago Manual of Style treats these s-fraught instances in a few different ways.

    First, your typical plural noun ending in s receives a solo apostrophe, sans the added s, while a singular noun ending in s—think bass—gets the apostrophe and added s, like any other noun would (CMOS 7.16).

    Next, solo proper nouns ending in s get the standard apostrophe + s, the Jones’s for example (CMOS 7.17), while plural proper nouns receive a singular apostrophe. Seems pretty simple right?

    BUT, when the singular and plural forms of the noun are the same—think species—both forms only receive a solo apostrophe to form the possessive. The Chicago Manual of Style also recommends recasting a sentence to avoid the possessive if confusion is likely. This rule also applies to singular entities that are plural, such as the United States (CMOS 7.20).

  5. Punctuation: In and around quotation marks.
  6. To round out our list we have some wonky rules around punctuation, specifically how punctuation functions in and adjacent to quotation marks and parenthesis. First, what you will find is that different punctuation marks have different rules. You would think that commas and semicolons would be treated in a similar fashion. Not so!

    Periods and commas are included inside of quotation marks, unless you are British or identifying a file name using quotation marks at the end of a sentence. For example:

    He described what he heard as a “short, sharp shock.” (CMOS 6.9)


    If your server uses “index.html” as its default file name, the name of your own default file cannot be “index.htm”. (CMOS 7.79)

    Semicolons, as promised, are treated differently than commas and periods and are placed outside of quotation marks, as are colons. And finally, question marks and exclamation points follow quotation marks, unless they are part of the quote itself (CMOS 6.10).

    Table showing rules for punctuation relative to quotation marks and parenthesis

    Indeed, these rules are so often confused that Chicago has a table devoted to explaining where punctuation lands with regard to quotation marks and parenthesis.

So next time you encounter one of these instances while writing or editing, don’t worry. The answers you seek exist complete with their many exceptions.

question marks on a brown background

Style Guide, Style Sheet—What’s the Difference?

One of the things I was most confused about when I first started editing with Ooligan was the difference between a style guide and a style sheet. There were a lot of times during my first term when I thought they were the same thing. With some hands-on practice—and the help of the editorial department—I soon learned that they are not the same and are actually quite different. For anyone who has been in a similar situation, here’s everything you need to know about style guides and style sheets.

Style Guides

Think of a style guide as a collection of rules and suggestions that editors use to ensure that everything follows a consistent set of guidelines. The style guide that is predominantly used in publishing is The Chicago Manual of Style (CMOS), although there are others such as the AP Stylebook and the Publication Manual of the American Psychological Association (APA). According to the Chicago website, “The Chicago Manual of Style is the venerable, time-tested guide to style, usage, and grammar . . . It is the indispensable reference for writers, editors, proofreaders, indexers, copywriters, designers, and publishers, informing the editorial canon with sound, definitive advice.” CMOS has rules on everything: capitalization, hyphenation, the treatment of numerals, abbreviations, punctuation, and even formatting. As I like to say, there is a rule for everything, and Chicago lists every rule.

A related document that you will come across is the in-house style guide. Sometimes an individual publishing house or press will deviate from the standard style guide, and these deviations are tracked in the in-house style guide. Think of an in-house style guide as a supplement to the major style guide that is specific to the press or publishing house. For example, if your press has guidelines on hyphenating compound words that differ from the guidelines in CMOS, these will be documented in the in-house style guide. Just like the standard style guide, it is expected that anyone who edits for the press follows these guidelines. I highly recommend browsing this article from Grammar Girl for more information.

Style Sheets

Unlike style guides, style sheets are unique to each manuscript or document. While style guides serve as an overarching umbrella of guidelines for all manuscripts, style sheets outline the specifics of each manuscript, and the overall goal is to create consistency. Think of a style sheet as a reference document that is created so that anyone who works on the project can see exactly how things should be spelled, formatted, and styled. Style sheets can outline everything from the proper spelling of names/characters/places in the manuscript, how to treat numbers and hyphens, and even when to capitalize or italicize certain words or phrases. Check out this website for more information on style sheets.

Style guides and style sheets are both important documents to use when editing. Both style guides (standard and in-house) outline the style, grammar, and layout guidelines that the manuscript should follow. Editors should be familiar with both style guides and consistently apply them to the manuscript. Style sheets are just as important, and as an editor, you should always be sure that you match what is on the style sheet for the manuscript you are working on.

I hope this helps clarify the differences between style guides and style sheets! Happy editing!