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