The controller shifts available {HEAD ~ power} between the first lighting source and {TAIL ~ the second lighting source} 
between
The controller shifts available { HEAD ~ power } between the first lighting source and { TAIL ~ the second lighting source }
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL