Journal of Digital Information Management Su-Cheng Haw, Chien-Sing Lee 5 3 2007 http://www.dirf.org/jdim/v5n3a10.asp With the popularity of XML as data exchange over the Web, querying XML data has become an important issue to be addressed. Since the logical structure of XML is a tree, establishing a parent-child (P-C), ancestor-descendant (A-D) or sibling relationship between nodes is essential for structural query processing. Thus, we propose using a <self–level: parent> labeling scheme to encode each element in the XML database by its positional information. Based on this labeling scheme, we further propose our TwigINLAB algorithm to optimize the query processing. Experimental results indicate that TwigINLAB can process both path queries and twig queries better than the TwigStack algorithm on an average of 27% and 14% respectively in terms of execution time using the XMARK benchmark dataset.