Wall 31 has formed therein a hole 32 bounded by {TAIL ~ a circumferential margin} 33 provided by {HEAD ~ wall} 31 
Wall 31 has formed therein a hole 32 bounded by { TAIL ~ a circumferential margin } 33 provided by { HEAD ~ wall } 31
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH