{HEAD ~ The drain region}, {TAIL ~ the source/base region}, and the cathode region have a second conductivity type 
{ HEAD ~ The drain region } , { TAIL ~ the source / base region } , and the cathode region have a second conductivity type
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH