{HEAD ~ The motor} is powered by {TAIL ~ a power supply}, e.g., a battery pack, located within the housing 
{ HEAD ~ The motor } is powered by { TAIL ~ a power supply } , e.g. , a battery pack , located within the housing
HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH