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Consider the following two sentences:

Statement 1:

The parameters were calculated a priori, and the other variables were calculated iteratively.

Statement 2:


This may seem trivial, but the only difference between the two sentences is the way in which the , has been formatted. In the first statement the , is in italics. In the second, the , is not in italics. Does it depend on the writer whether or not to italicize the punctuation marks adjoining the affected words? Or is there a definite rule governing this? The same question can be extended to other types of formatting, e.g. bold.

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closed as not constructive by Kris, StoneyB, tchrist, MετάEd, Robusto Nov 10 '12 at 15:10


I really don't think the vast majority of readers will see the difference. –  Robusto Nov 10 '12 at 15:10
It was likely a typo. They grabbed one character too many. –  mhoran_psprep Nov 10 '12 at 16:00

2 Answers 2

up vote 6 down vote accepted

Here's one style manual's answer to that question:

Italics do not include punctuation marks (end marks or parentheses, for instance) next to the words being italicized unless those punctuation marks are meant to be considered as part of what is being italicized: "Have you read Stephen King's Pet Semetary?" (The question mark is not italicized here.) Also, do not italicize the apostrophe-s which creates the possessive of a title: "What is the Courant's position on this issue?"

This is really a style-manual problem, not an English usage or grammar problem. Each publication has its house style. Newspapers have their own style manuals, academic fields have theirs, and technical fields have theirs. There is no definite rule.

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And you may have yours. –  Noah Nov 10 '12 at 6:13
I definitely do. –  user21497 Nov 10 '12 at 6:55
While this answer is broadly correct, it doesn't include the case of a simple comma -- is that considered part of the what is being italicised? I would say Yes and the comma in Example 1 is correct. If you were to write He said "a priori," and misused the term, then the quotes should not be italicised but the comma should as it's attached to the word. The comma after term there is bold for the same reason. –  Andrew Leach Nov 10 '12 at 8:06
@Andrew Leach: This seems to me a matter of judgment and preference rather than of rule. The journals I edit papers for are frequently inconsistent about such things. Some, e.g., want volume no. of cited journals in bold but not the colon or comma that immediately follows it, & some want both in bold. Strictly house style. The rule that site I linked to gives about apostrophe-s, however, seems standard regardless of the manual consulted. –  user21497 Nov 10 '12 at 8:29

English isn't a matter of rules on tablets of stone so much as a matter of communication, so really you should follow house style or whatever your readers find easiest.. But as a matter of logic, the comma should not be in italics; the phrase you want to italicise is 'a priori', which does not include the comma. On the other hand, 'i.e.', assuming you wish to italicise it, does include punctuation, so the full stops should also be in italics.

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