Each device 32 is held on the fixture by a vacuum in {TAIL ~ the headspace} above {HEAD ~ the device} 32 
Each device 32 is held on the fixture by a vacuum in { TAIL ~ the headspace } above { HEAD ~ the device } 32
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH