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