3. The article of manufacture of claim 1 , wherein the means is further for: analyzing the difference operation configuration information to yield equivalent nodes and ignorable nodes, and applying the difference operation configuration information to the tree-structured documents, to select nodes among the tree-structured documents that are considered equivalent, and to select nodes among the tree-structured documents that are to be ignored.
1. An article of manufacture comprising: a non-transitory computer-readable storage medium; and, means in the medium for: performing a difference operation on at least two tree-structured documents, the tree-structured documents being different from one another and each of the tree-structured documents comprises a plurality of nodes, the difference operation performed in accordance with difference operation configuration information regarding the tree-structured documents, performing a merging operation on the tree-structured documents from correspondence information generated based on the difference operation configuration information regarding the tree-structured documents, the correspondence information is in eXtensible Markup Language (XML) comprising a list of nodes that are only in one of the tree-structured documents, each node within the list of nodes of the correspondence information specifying in which of the tree-structured documents the node is located, and generating the difference operation configuration information from difference operation configuration information meta data, the difference operation configuration information meta data being created by a user, wherein the difference operation configuration information specifies a priori one or more nodes among the tree-structured documents that are to be considered equivalent when the difference operation is performed, and specifies a priori one or more nodes among the tree-structured documents that are to be ignored when the difference operation is performed, where the nodes that are to be considered equivalent are non-identical nodes, such that the difference operation and the merging operation are tuned to expectations of the user, since the difference operation configuration information is generated from the difference operation configuration information meta data created by the user.