In particular, {HEAD ~ if failure} of {TAIL ~ a CB server} 380 n is detected in stage 810, operation 800 proceeds to stage 820 
In particular , { HEAD ~ if failure } of { TAIL ~ a CB server } 380 n is detected in stage 810 , operation 800 proceeds to stage 820
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH