Style rules used to suggest an apostrophe for initialized items such as C.D.'s for sale. Of course, modern style rules suggest CDs for sale (but don't tell the New York Times).
The Times’ style guide would render more than one compact disc as C.D.s (no apostrophe, but with periods in intialisms).
Do you have a link to any authoritative style guide that suggested “C.D.’s”? The Times' guide (2015) demands apostrophes to pluralize single letters: “the word has two t’s”. I think that’s silly, just as their use of quotation marks rather than italics for book titles.
Here is a quote from the 2015 edition of the Style Guide:
“G.I. The colloquial term, derived from government issue, for American soldiers. The plural is G.I.s”
I've probably gotten confused about the single letters and the C.D.s, thanks. (actually, looking at the other response's link, the Times may likely have changed their style guide)
But, then why an apostrophe for t's and not for fees? :D It rhymes, it should be punctuated the same is as good a rule as any!
Do you have a link to any authoritative style guide that suggested “C.D.’s”? The Times' guide (2015) demands apostrophes to pluralize single letters: “the word has two t’s”. I think that’s silly, just as their use of quotation marks rather than italics for book titles.
Here is a quote from the 2015 edition of the Style Guide:
“G.I. The colloquial term, derived from government issue, for American soldiers. The plural is G.I.s”