A dom view gives a cursor in sync on the text with the audio being spoken from a .wav file of the xml source. The student says, whoa, go back. Back' like this has to be interpreted wrt to context. Similarly other 'goto' type instructions. UP is a good one.
Any student wants to annotate a book.
HTH DaveP Sounds to me like a pretty compelling argument that not having xPath available would require you to re-invent most of the xPath wheel.