According to one embodiment of the invention, the pockets are defined by {HEAD ~ upstanding walls} in the movable element adjacent the surface exposed to gases of {TAIL ~ combustion} 
According to one embodiment of the invention , the pockets are defined by { HEAD ~ upstanding walls } in the movable element adjacent the surface exposed to gases of { TAIL ~ combustion }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL