storing the protection level of {TAIL ~ each} of {HEAD ~ the set} of data stored in the leaf nodes; and 
storing the protection level of { TAIL ~ each } of { HEAD ~ the set } of data stored in the leaf nodes ; and
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH