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