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