The method 1, wherein ascertaining whether the fault exists comprises determining {HEAD ~ a type} of {TAIL ~ the fault} 
of
The method 1 , wherein ascertaining whether the fault exists comprises determining { HEAD ~ a type } of { TAIL ~ the fault }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL