Indexes without page numbers?

Consider the following example from an index from a book in the public domain:

State Trees, 354-7; of, Idaho, 354-5; Illinois, 355

If I turned this book into a reflowable epub, then the page numbers wouldn't make sense. So how do most epub authors handle this kind of situation?

Since epubs are searchable, I've thought of just creating a static index (i.e. no links) that lists key words that readers can then search for. (However, it wouldn't work for the example I posted above, which would have to be customized somehow.)

Have you ever seen such an index in an epub?