“…The reasoning behind this is based on various methods to do with query rewriting. This concept is presently beyond the scope of our work, however, we do direct you to their purposes in (Fan et al, 2004;di Vimercati et al, 2005;Almendros-Jimenez et al, 2008). xpred(axis, query), represents an XPath predicate, where axis is the location of the node to apply the predicate query on.…”