interaction between the cam follower and {TAIL ~ the cam curvilinear surface} creating {HEAD ~ a plurality} of pushbutton equilibrium states 
interaction between the cam follower and { TAIL ~ the cam curvilinear surface } creating { HEAD ~ a plurality } of pushbutton equilibrium states
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH