6. The article of manufacture of claim 1 , wherein each of the tree-structured documents is an eXtensible markup language (XML)-formatted document.
6. The article of manufacture of claim 1 , wherein each of the tree-structured documents is an eXtensible markup language (XML)-formatted document. 7. The article of manufacture of claim 6 , wherein each of the XML-formatted documents comprises: at least one non-leaf element node; at least one leaf text node, each leaf text node having one label, value; and, at least one leaf attribute node, each leaf attribute node having two labels, name and value.