The loading, unloading, {HEAD ~ handling} and processing of {TAIL ~ wafers} in the machine can occur while other wafers are being preheated 
The loading , unloading , { HEAD ~ handling } and processing of { TAIL ~ wafers } in the machine can occur while other wafers are being preheated
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH