Q. I believe this may have been addressed back in the 14th edition, but I cannot find a current rule to support my writing “Yes sir!” as an exclamation (or “Yes ma’am!”) in the manner of “Aye sir!” Would you please let me know what CMOS’s view is on this? I have been leaving out the comma and am now being challenged by publishers I’m editing for.
A. You are fine either way. In direct address, a comma before the addressee is traditional and acceptable: “Yes, Virginia, there is a Santa Claus.” However, as noted in CMOS 5.47 of the 14th edition, expressions like “yes sir!” may be considered almost as a single word and omit the comma, especially when a true direct address follows (“Yes sir, Uncle Howard!”).