A ring is rotatably mounted to the cylindrical top and has {HEAD ~ three notches} defined in {TAIL ~ an inner periphery} thereof 
defined in
A ring is rotatably mounted to the cylindrical top and has { HEAD ~ three notches } defined in { TAIL ~ an inner periphery } thereof
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH