{HEAD ~ The repair server} maintains {TAIL ~ an ordered list} of the retransmit servers that are most likely to have buffered copies of packets missing from the session 
{ HEAD ~ The repair server } maintains { TAIL ~ an ordered list } of the retransmit servers that are most likely to have buffered copies of packets missing from the session
HEAD 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 OTH OTH OTH OTH