In the United States, the leading style guides are The Chicago Manual of Style and The Associated Press Stylebook. The former is widely adopted throughout the publishing industry; the latter is mostly used by news organizations. Both are available in print and online, though not for free. Some scholarly and professional organizations have their own style guides, though these usually focus more on documenting references than on punctuation. Writers short of cash, as well as those preparing documents for the United States government, should consult the United States Government Publishing Office Style Manual, which is available for free at https://www.govinfo.gov/app/details/GPO-STYLEMANUAL-2016.
When style issues are implicated in this guide, I have usually deferred to The Chicago Manual of Style, 17th edition. The few deviations are noted within the guide.
The following chart shows some of the major differences in punctuation style between The Associated Press Stylebook (2018 edition) and The Chicago Manual of Style (17th edition).
| The Chicago Manual of Style | The Associated Press Stylebook | |
|---|---|---|
| Serial comma | Rule: Include a comma before the conjunction.
Example: My favorite composers are Beethoven, Brahms, Mahler, and Mozart. |
Rule: Do not include a comma before the conjunction.
Example: My favorite composers are Beethoven, Brahms, Mahler and Mozart. |
| Spacing between initials in name | Rule: Include a space between initials.
Example: E. L. Doctorow |
Rule: Do not include a space between initials.
Example: E.L. Doctorow |
| Abbreviations | Rule: Preference against periods.
Example: JD, BA, PhD, BCE (referring to the era), PO Box, US, UN |
Rule: Preference for periods.
Example: J.D., B.A., Ph.D., B.C.E., P.O. Box, U.S., U.N. |
| Possessives of singular proper nouns ending in s | Rule: Add an apostrophe and s.
Example: Texas’s, James’s, Xerxes’s |
Rule: Add only an apostrophe.
Example: Texas’, James’, Xerxes’ |