library and command line utility for diffing xml files

 xmldiff is a library and a command-line utility for making diffs
 out of XML. This may seem like something that doesn't need a
 dedicated utility, but change detection in hierarchical data is
 very different from change detection in flat data. XML type formats
 are also not only used for computer readable data, it is also often
 used as a format for hierarchical data that can be rendered into human
 readable formats. A traditional diff on such a format would tell you
 line by line the differences, but that would not be readable by a human.
 xmldiff provides tools to make human readable diffs in those situations.
 .
 This package provides two possible commands: xmldiff and xmlpatch.
 .
 The diff algorithm is based on _Change detection in hierarchically
 structured - information_, by S. Chawathe, A. Rajaraman,
 H. Garcia-Molina and J. Widom, - Stanford University, 1996.