I've completed all of the 54 chapters in my book and I now want to index it. The paradigm seems to be different than what I thought it was. For an index entry to be processed for all of the chapters in the book (Add to All), do all the chapters have to be loaded in InDesign at the same time? I would have thought (since I have all the chapters listed in my book file) that it would automatically search all of those files, whether they are currently loaded or not. That does not appear to be the case. Am I confused or do all the chapters really have to be loaded for InDesign to find all the occurrences of an index entry? Thank you.
If you want to have InDesign place index markers in all the chapters of your book, yes, you do have to have the chapters open for InDesign to find them.
The Book panel has extraneous pointers to coordinate book pagination and sort order, as well as output functions coordinated through those markers. But if you need to access the text inside those InDesign documents, like you would to place index markers inside the chapter text, you need to, well, open the text inside those documents so InDesign can access them.
Think of the Book features as a superstructure surrounding the documents, rather than a piece inside each of the documents.
It's tedious, but necessary. You have to have the documents open to access the text and place index markers for a given text reference throughout your book using the Add All button.
Hope this helps,