{HEAD ~ The second control signal} is coupled to an input of the NAND gate and inactivates {TAIL ~ the first control signal} 
{ HEAD ~ The second control signal } is coupled to an input of the NAND gate and inactivates { TAIL ~ the first control signal }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL