The chambers 212A, {HEAD ~ 212B} which represent {TAIL ~ the bottleneck chambers}, may have a “time” to next planned maintenance of 3000 and 12000 substrates, respectively, while the chambers 213A, 213B may have times corresponding to 2500 and 9000 substrates, respectively 
represent
The chambers 212A , { HEAD ~ 212B } which represent { TAIL ~ the bottleneck chambers } , may have a “ time ” to next planned maintenance of 3000 and 12000 substrates , respectively , while the chambers 213A , 213B may have times corresponding to 2500 and 9000 substrates , respectively
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH REL TAIL 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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH