13. The computer readable medium of claim 12 , further comprising computer program instructions for: receiving a query from the user, wherein the query requests access to a node in the structured document; executing the query; evaluating the value expression corresponding to the path associated with the requested node; displaying data associated with the requested node if the value expression grants access to the user; and hiding data associated with the requested node if the value expression denies access to the user.
14. The computer readable medium of claim 13 , wherein the evaluating is performed during a run time.