{TAIL ~ An actuator knob} is manually accessible to {HEAD ~ the user} and may be fixed axially to the outer housing 
{ TAIL ~ An actuator knob } is manually accessible to { HEAD ~ the user } and may be fixed axially to the outer housing
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH