In accordance with the invention, a range of possible threshold voltages for {HEAD ~ a memory cell} in {TAIL ~ a multibit} per cell memory is divided into allowed states associated with data values and forbidden zones between the allowed states 
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In accordance with the invention , a range of possible threshold voltages for { HEAD ~ a memory cell } in { TAIL ~ a multibit } per cell memory is divided into allowed states associated with data values and forbidden zones between the allowed states
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL 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