receiving a request to write {HEAD ~ the predetermined data} to a page to which {TAIL ~ data} has been written 
receiving a request to write { HEAD ~ the predetermined data } to a page to which { TAIL ~ data } has been written
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH