In {TAIL ~ writing}, the n transistors in the read circuits form with two p transistors NOT circuits whose outputs form {HEAD ~ the data lines} 
In { TAIL ~ writing } , the n transistors in the read circuits form with two p transistors NOT circuits whose outputs form { HEAD ~ the data lines }
OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD