The user, vendor, manufacturer and other supplier may maintain {HEAD ~ databases} housed on {TAIL ~ the central computers} 
housed on
The user , vendor , manufacturer and other supplier may maintain { HEAD ~ databases } housed on { TAIL ~ the central computers }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL