From this session S1, the client 20 can perform {TAIL ~ 610 changes} to {HEAD ~ the feature instances} F1 and F2 
From this session S1 , the client 20 can perform { TAIL ~ 610 changes } to { HEAD ~ the feature instances } F1 and F2
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH