34. The method of claim 33 , wherein the calculated relative positional values further relate to the proximity to each other of the primitive graphic elements in the pair.
33. A method for analyzing a document, the method comprising: receiving the document that comprises a plurality of primitive graphic elements, each primitive graphic element defined as a single object in the document, the document having a drawing order that indicates the order in which the primitive graphic elements are drawn when the unstructured document is displayed; calculating relative positional values for each pair of successive primitive graphic elements in the drawing order, wherein the calculated relative positional values relate to a size of the primitive graphic elements in the pair; based on the calculated relative positional values, defining a cluster of successive primitive graphic elements; identifying a set of sub-clusters of primitive graphic elements in the cluster that satisfy particular constraints; and defining each particular sub-cluster as a single structural graphic element within the document comprising the primitive graphic elements in the particular sub-cluster.