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Message: [QUOTE="blmblm, post: 4201555"] "[sic]"? My understanding is that while it's less common than it used to be to form the plurals of multiletter acronyms [*] with apostrophes (e.g., "CDs" rather than "CD's"), apostrophes are still advised for forming plurals of single letters, to avoid ambiguity in the case of A and I (and possibly some others I'm not thinking of). Can you cite any authoritative recommendation for leaving out the apostrophes here? [*] Or initialisms, for the pedantic? [ snip ] [ snip ] [/QUOTE]