tree to tree correction between xml documents

 Xmldiff is a utility for extracting differences between two xml
 files. It returns a set of primitives to apply on source tree to
 obtain the destination tree.
 .
 The implementation is based on _Change detection in hierarchically
 structured - information_, by S. Chawathe, A. Rajaraman,
 H. Garcia-Molina and J. Widom, - Stanford University, 1996