An experiment by Julie Blanc – https://gitlab.pagedmedia.org/tools/experiments/tree/master/book-index
It works by looking for a class within the text and adding that item to the index (and grouping duplicates). We are writing up a Feature Proposal to discuss at the next Editoria community meet. Essentially we would use Wax to annotate Index items. For this we need professional indexers to design such a tool with us. We’ll write this up and propose it and see where it goes.