Grammatically Correct: The writer's essential guide to punctuation ...

PUNCTUATION
Zelda apparently has only one brother, and his name happens to
be Mark. She also, quite properly, has only one husband, and his
name happens to be Hal.
Zelda showed up at the party with her brother Mark and her husband
Hal.
Zelda apparently has more than one brother and has brought the
one named Mark to the party; on the husband front, she has some
explaining to do.
The next-door neighbors, a pair of curmudgeonly retirees, would sit on
their porch and hurl insults at passing squirrels.
The next caller, a doctor, defended the policy.
The old rocking chair, the one that had sat unused in the basement for
years, fetched eight hundred dollars.
Teachers using the controversial book were strong defenders of its
usefulness.
Mimi, the neighbor two doors down, was organizing a street sale.
Mr. Douglas the storekeeper warned Mr. Douglas the street vendor
to stay off his turf.
The house with the rock garden is up for sale.
The downtown core, once considered doomed, is making a comeback.
Art once viewed as valueless is now commanding high prices.
Clauses too can act as restrictive or nonrestrictive descriptors,
as described next.
IF A DEPENDENT CLAUSE IS NONRESTRICTIVE, MARK IT OFF
WITH COMMAS. IF IT IS RESTRICTIVE, DO NOT USE COMMAS
As described in "Basic Sentence Structure" on page 55, in one type
of dependent clause, the subordinating word is a pronoun. This type
of dependent clause can function as a restrictive or nonrestrictive
descriptor, the same way that a word or a phrase can.
To illustrate: Suppose we have a passage of text that describes
two men approaching, one of them dawdling behind the other. The
reader is then told:
The man who had lingered behind suddenly quickened his pace.
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