There is provided a mechanism for conducting data transmission from a network management entity of communication network control element to a terminal or UE with improved robustness. An apparatus for same includes means for defining an access control policy for a user of the XML document and means for deriving a security view of the XML document for the user based on said access control policy and schema level processing of the XML document. The inertial valve does not open in response to rider-induced forces. The gate insulator layer covers the first and second gate electrodes. 0 nor more than 200 when intensity ratios of respective {001}<470>, {116}<6 12 1>, and {223}<692> directions in a sheet plane by X-ray diffraction are set to A, B, and C respectively and Z=0.