Thereafter, the bids forming this combination can be declared the winning bids of the auction, {HEAD ~ reverse auction} or {TAIL ~ exchange} 
Thereafter , the bids forming this combination can be declared the winning bids of the auction , { HEAD ~ reverse auction } or { TAIL ~ exchange }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL