10. The method of claim 8 wherein each of the first and second document tree structures includes a plurality of subtree structures, and wherein aligning the first and second document tree structures comprises: aligning nodes in the subtree structures to obtain subtree alignments; and aligning the plurality of subtree structures, to align the first and second document tree structures, based on the subtree alignments.
10. The method of claim 8 wherein each of the first and second document tree structures includes a plurality of subtree structures, and wherein aligning the first and second document tree structures comprises: aligning nodes in the subtree structures to obtain subtree alignments; and aligning the plurality of subtree structures, to align the first and second document tree structures, based on the subtree alignments. 12. The method of claim 10 wherein aligning the plurality of subtree structures comprises: aligning the plurality of subtree structures while maintaining a hierarchy and sequence of the plurality of subtree structures relative to one another and of nodes in the subtree structures relative to one another.