In other words, the judgment is made on the type of {HEAD ~ the received document data} in {TAIL ~ this step} 
In other words , the judgment is made on the type of { HEAD ~ the received document data } in { TAIL ~ this step }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL