The browser assembles the file one byte at a time on the users computer so that the user has {HEAD ~ a modified copy} of {TAIL ~ the original file} 
of
The browser assembles the file one byte at a time on the users computer so that the user has { HEAD ~ a modified copy } of { TAIL ~ the original file }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL