{HEAD ~ The repository} determines {TAIL ~ upgradeable files} currently installed on the device based on the current state information, and checks for file updates for the upgradeable files 
{ HEAD ~ The repository } determines { TAIL ~ upgradeable files } currently installed on the device based on the current state information , and checks for file updates for the upgradeable files
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH