CMOS 16 CHANGES, #9

When used as a title/heading, should the second part of a hyphenated word be capitalized or not (examples: Chapter Twenty-One, Fifty-first Street)?

CMOS-15, rule 8.170, said the second word should be lowercased (as in Lolita’s Twenty-first Birthday) except when it’s part of a multiple-word compound (such as Twenty-First-Century History).

CMOS-16, rule 8.159, now suggests capitalizing the second element.