{TAIL ~ A highly scalable, flexible, and extensible mechanism} is provided for authenticating a request from {HEAD ~ a client} 
{ TAIL ~ A highly scalable , flexible , and extensible mechanism } is provided for authenticating a request from { HEAD ~ a client }
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD