An appositive is a word or phrase that refers to the same idea as another word or phrase in proximity. The phrase “my friend John” contains two appositives, because “my friend” and “John” are two ways of identifying that person I know well.
For many writers, how to punctuate appositives is problematic. Here are some erroneous uses of punctuation with appositives:
1. “My sister Jane is a pain.”
Whether this sentence is correct or not, actually, depends on specific knowledge: Does the writer have more than one sister? If so, the sentence is correct. If not, this sister’s name should be set off by commas, and a clarifying modifier like older (unless there are two or more sisters of greater age) preceding her name would be helpful.
If you’re editing such a sentence, and you don’t have details, it’s best to omit commas. (Traditionally, father or mother would imply that the person in question is in a class all by himself or herself, necessitating commas, but it’s possible to have more than one of each.)
2. “This year’s spotlights include a tribute to Asian American film legend, Anna May Wong.”
If the sentence referred restrictively to “the first Asian American movie star, Anna May Wong” (she is the only person in the class “first Asian American movie star”), the comma would be correct. But the adjectival phrase “Asian American film legend” is merely what is called a temporary epithet; it could refer to other people as well.
The error perhaps derives from confusion with the correct construction “Anna May Wong, the Asian American film legend.” But as is, the sentence should have no comma.
3. “The typical manufacturing worker earned $44,680 last year, according to the New York-based research firm, Towers Perrin.”
This error mirrors that in the preceding example; it can afflict references to inanimate entities as well as descriptions of people. The comma preceding the firm’s name erroneously implies that only one New York-based research firm exists, and it is therefore erroneous (unless there was a previous reference, not by name, to the specific company).
4. “The crowd was being seated for the performance artist’s newest show Say No More.”
The opposite problem is on display here. The phrase “newest show” restricts the show title; only one show by the performance artist can be his or her newest, so a restrictive comma after show is necessary. The phrase “the performance artist’s show Say No More,” however, includes no qualifiers and therefore requires no comma.
5. “I read the book, The Chicago Manual of Style, from cover to cover in one sitting.”
In trumpeting this masochistic achievement, the writer is suggesting that the volume in question is the only one in existence; it is “the book.” But bibliophiles have other options, so the writer should respect that fortunate fact by omitting both commas from this sentence.