{HEAD ~ Portion} of {TAIL ~ data stream} or data block 200 is sent from one or more clients  
{ HEAD ~ Portion } of { TAIL ~ data stream } or data block 200 is sent from one or more clients
HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH