a) means for storing {HEAD ~ values} of {TAIL ~ voltage and power measurements} made at the load, 
of
a ) means for storing { HEAD ~ values } of { TAIL ~ voltage and power measurements } made at the load ,
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH