Thus, either the case must float, or {HEAD ~ isolation} of {TAIL ~ pacer pulses} must be provided 
Thus , either the case must float , or { HEAD ~ isolation } of { TAIL ~ pacer pulses } must be provided
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH