All requests for {TAIL ~ a cache line} are screened by the blocker associated with {HEAD ~ each home directory} 
All requests for { TAIL ~ a cache line } are screened by the blocker associated with { HEAD ~ each home directory }
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD