In {TAIL ~ the case} of {HEAD ~ a negative logic signal}, the signal is active low where the logically true state corresponds to a logic level zero 
In { TAIL ~ the case } of { HEAD ~ a negative logic signal } , the signal is active low where the logically true state corresponds to a logic level zero
OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH