11. The computer readable medium of claim 10 , further comprising computer program instructions for: storing each path and corresponding generated value expression in a table.
11. The computer readable medium of claim 10 , further comprising computer program instructions for: storing each path and corresponding generated value expression in a table. 15. The computer readable medium of claim 11 , further comprising computer program instructions for: replacing the value expression for a path associated with a node with a reference notation if the value expression is identical to that for a path associated with the node's parent, thereby eliminating repeated value expressions in the table.