When the erase operation starts, an erase pulse is first applied only to {TAIL ~ the memory cells} connected to {HEAD ~ the word line} WL0  
When the erase operation starts , an erase pulse is first applied only to { TAIL ~ the memory cells } connected to { HEAD ~ the word line } WL0
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH