Each of said side surfaces has {TAIL ~ an inset}, 22A and 22B, spanning from {HEAD ~ the block top surface} 10 to the block bottom surface 8 
Each of said side surfaces has { TAIL ~ an inset } , 22A and 22B , spanning from { HEAD ~ the block top surface } 10 to the block bottom surface 8
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH