In {HEAD ~ such a construction}, {TAIL ~ the control signal} is applied to the digital to analog converter 
In { HEAD ~ such a construction } , { TAIL ~ the control signal } is applied to the digital to analog converter
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH