Q. I frequently edit indexes for heavily illustrated books. The indexer has been instructed to index the photographs. The result can be somewhat strange:

McIntosh apples, 231, 231

Can’t the reader assume that a photo page might also have text on it? Or is it better to break out the italic numbers separately? And should the text page precede the italic page when they are the same number? Also, how should the italic (or bold) page numbers be treated when there is a range of text pages with photos dropped in?

McIntosh apples, 231–235, 234–235

A. CMOS ignores these indexing dilemmas, perhaps because no single solution stands out as the best one. Indexers decide how to handle references to illustrations depending on how heavily illustrated the book is, how much room there is for an index, and other factors. All of the choices you describe are reasonable. If you think a particular method is expedient but might need explaining, add a headnote or footnote to the first page of the index.