One of the layers may be left unencrypted to allow {TAIL ~ free browsing} of {HEAD ~ a low quality service level} 
One of the layers may be left unencrypted to allow { TAIL ~ free browsing } of { HEAD ~ a low quality service level }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD