Processing from either process block 1140 or {HEAD ~ process block} 1150 terminates at {TAIL ~ END block} 1155 
terminates at
Processing from either process block 1140 or { HEAD ~ process block } 1150 terminates at { TAIL ~ END block } 1155
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH