“{HEAD ~ C}” are the fourth linguistic values 60 of {TAIL ~ the projected unit power costs} 
“ { HEAD ~ C } ” are the fourth linguistic values 60 of { TAIL ~ the projected unit power costs }
OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL