{HEAD ~ a lock} connected to {TAIL ~ the on/off switch}, the lock moving between a locked condition and an unlocked condition, the lock including elements which prevent the on/off switch from changing between the on condition and the off condition or between the off condition and the on condition when the lock is in the locked condition and which permit the on/off switch to change between the on condition and the off condition or between the off condition and the on condition when the lock is in the unlocked condition, 
{ HEAD ~ a lock } connected to { TAIL ~ the on / off switch } , the lock moving between a locked condition and an unlocked condition , the lock including elements which prevent the on / off switch from changing between the on condition and the off condition or between the off condition and the on condition when the lock is in the locked condition and which permit the on / off switch to change between the on condition and the off condition or between the off condition and the on condition when the lock is in the unlocked condition ,
HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH