Apple has something called Fixed Layout ePub, that's especially useful for making an iBook of a heavily illustrated children's book with a specific layout of the text and illustrations.
I have found guides that explain how to make a Fixed Layout ePub (Threepress is the best tutorial I found), and I can now make a Fixed Layout ePub just fine. Yay!
But... if you go into an Apple store and fire up iBooks on one of their iPads, you will see the children's book Olivia, and others, that feature text overlapping illustrations. The text is not just part of the graphic — it's true, selectable text.
So how did they do it? Anyone know? You would think this information would be easily locateable, but so far I haven't found a thing. Somebody must know, or the Olivia book wouldn't exist.
(Note: This question is about how to write the actual HTML in the ePub file that will show selectable text overlapping an illustration. I don't want to create a book in some word processor or page design app and then convert it to ePub.)