Here is a punctuation question from FB that inspired today’s blog:
“On examination her lower extremities had normal capillary refill — that is, normal circulation — and no trophic changes, in other words, none of the signs of RSD.”
Often people want to redefine or further explain what they have just said. We will deal here with this situation when the person uses one of these words to “introduce” what he wants to explain:
that is in other words
i.e. for instance
for example namely
e.g. to wit
These elements function as parentheticals, elements that are not needed in the sentence. Parentheticals are always surrounded by punctuation.
When one of these is used with a “renaming” — we would call this an appositive — where it is in the sentence and what comes after it is what is going to determine the punctuation.
AT THE END OF THE SENTENCE:
If there is a fragment after the parenthetical, use a pair of commas around it.
…a car, that is, a Toyota.
…my doctor, that is, Dr. Freeman.
If there is a complete sentence after the parenthetical, use a semicolon in front and a comma after.
…a car; that is, I bought a Toyota.
…my doctor; that is, I saw Dr. Freeman.
If there is a list after the parenthetical, use a colon in front and a comma after.
…new cars: that is, Toyotas, Fords, Hondas.
…several doctors: that is, Dr. Freeman, Dr. Ross, and Dr. Howard
If there is a question in front of the parenthetical, use an interrog after the question and a comma after the parenthetical.
…Did you buy a new car? That is, a Toyota?
…Did you see your doctor? That is, Dr. Freeman?
When the entire sentence has finished and the parenthetical element renames the subject, use a dash in front of the parenthetical and a comma after.
…We walked a long distance before coming to the gas station where we found assistance — that is, John and I.
…He was unable to get up as he seemed to be pinned under the edge of the bumper — that is, my brother.
IN THE MIDDLE
If the element is in the middle, use a dash in front of the parenthetical, a comma after it, and a dash after the whole element.
…bought a car — that is, a Toyota — before I left for school.
…saw the doctor — that is, Dr. Freeman — for the problem I was having.
I will be going over this in my punctuation workshop at NCRA in Philly.