{HEAD ~ The protect string} specifies the authentication scheme or schemes that need to be implemented for {TAIL ~ that request} 
{ HEAD ~ The protect string } specifies the authentication scheme or schemes that need to be implemented for { TAIL ~ that request }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL