The layers may be encrypted using a separate key for each layer, and {HEAD ~ rights} to {TAIL ~ a key} granted by permission 
The layers may be encrypted using a separate key for each layer , and { HEAD ~ rights } to { TAIL ~ a key } granted by permission
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH