Abbreviations

Q. Is it acceptable to use an acronym for the first time in a subheading? Or should an acronym only be used in the information that follows a subheading even if it’s the second time the word appears?

A. Although our mail reveals some demand for a rule in this regard, we can’t think of a good reason to allow or disallow various placements of an acronym. An acronym may be used anywhere it is helpful and not out-and-out ugly.

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]