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