the preprocessing module includes {HEAD ~ an elevator} and an elevator control capable of cooperating with the operation of the transport mechanism to position the rack to receive batches of {TAIL ~ wafers} of varying numbers of wafers without empty positions therebetween 
the preprocessing module includes { HEAD ~ an elevator } and an elevator control capable of cooperating with the operation of the transport mechanism to position the rack to receive batches of { TAIL ~ wafers } of varying numbers of wafers without empty positions therebetween
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH