If the transformed remote query element is pushdownable, the system adds {HEAD ~ the transformed remote query element} to {TAIL ~ a transformed inexact query output} 
If the transformed remote query element is pushdownable , the system adds { HEAD ~ the transformed remote query element } to { TAIL ~ a transformed inexact query output }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL