bus interface means for monitoring {HEAD ~ data} moved on {TAIL ~ said system bus} and for sensing via a hardware implemented protocol any modification of said moved data for storage of validity status information in said second directory means 
moved on
bus interface means for monitoring { HEAD ~ data } moved on { TAIL ~ said system bus } and for sensing via a hardware implemented protocol any modification of said moved data for storage of validity status information in said second directory means
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH