Today I received a question from a patron through meebo, but I never got the chance to fully answer the question.
Question: How do you punctuate a sentence that uses the abbreviation "etc." in a parenthetical phrase?
Here's the answer!
According to the Chicago Manual of Style, the abbreviation "etc." is always followed by a period (559). If, however, the abbreviation comes at the end of a sentence, then only one period is used (244).
He writes stories about ghosts, goblins, vampires, etc.
If an entire independent sentence is enclosed in parentheses, the period goes inside the closing parentheses. When information in parentheses is included within another sentence, the period belongs outside (244).
She eats eggs for breakfast every morning. (She owns several chickens.)
She eats eggs for breakfast every morning (except on Sunday when she sleeps late).
So, combining those two rules, the correct way to use "etc." within parentheses is like this:
On Sunday, she eats brunch at the diner (where they make waffles, pancakes, omelets, etc.).
On Sunday, she eats brunch at the diner. (She loves their waffles, pancakes, omelets, etc.)
I hope this answered your question, meebo patron! Let us know if we can help you again.
The Chicago Manual of Style. Chicago: The University of Chicago Press, 2003.