This body spaces {HEAD ~ a source region} of the second conductivity type from {TAIL ~ the drift region} 
from
This body spaces { HEAD ~ a source region } of the second conductivity type from { TAIL ~ the drift region }
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL