Now referring to FIG. 2A, shown is a schematic diagram of an illustrative tree data structure for a plurality of web pages 200A. A top level web page 202 branches into second level web pages 204A, 204B and 204C. Third level web pages 206A and 206B branch off from second level web page 204A, and each third level web page 206A and 206B has a plurality of web pages, 208A and 208B respectively, linked