{HEAD ~ Peers} that have not opened the pipe may not receive or send {TAIL ~ any messages} on that pipe 
{ HEAD ~ Peers } that have not opened the pipe may not receive or send { TAIL ~ any messages } on that pipe
HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH REL REL OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH