darcs and document object models

Hi!

Has anybody tried to get the patch theory work with xml files in a way,
that uses DOM semantics. How difficult would it be to implement this?

Im mostly interested in the case, where the document objects have some
kind of (globally) unique ID, which allows us to track how objects are
added, removed, changed of moved.

This would be a huge step towards having things like CAD models under
meaningful version control.

TIA,
Harald