Greetings, Mr. King:
Your post is most appreciated.
http://www.dailywritingtips.com/parenthetical-phrases/
Let’s say, for the sake of argument, that you’re explaining something in writing — such as which punctuation marks to use to signal a break in thought — and you want to make it clear to your readers (many of whom may never have realized that there are distinctions to be made). How would you do it?
I just did.
One of three basic strategies usually suffices to set a parenthetical phrase off from its root sentence. By “parenthetical phrase,” I mean one that constitutes a digression (or a clarification) — and, despite the name, it doesn’t have to involve parentheses.
I did it again.
You see, the mildest form of parenthesis, for when you want to quickly insert a detail without distracting the reader, is a subordinate clause: a nonessential phrase framed by a pair of commas. The preceding sentence includes a subordinate clause: the one that begins “for when” and ends “the reader.” If you temporarily remove that phrase from the sentence, its structural integrity remains intact. (Try it; I’ll wait — but don’t forget to put it back when you’re done.) The subordinate-clause parenthesis is one strategy.
There's more ... please read on, dear reader!
CoCo, Editor at Large