Possessives and Attributives

Q. Hello. I can’t find a clear answer to the question of how to form the possessive of an acronym, especially a plural one. For example, I see the use of an apostrophe without a following s used often (CBS’ programming). I think an s is appropriate in any case, including when the acronym itself is plural. Is this correct?

A. Chicago style treats acronyms like other words, adding an apostrophe and an s: CBS’s audience. Although a plural possessive acronym can be awkward, the apostrophe alone serves: the PDFs’ suitability. Please see CMOS 7.17.