The x ESDS displace both the DES and {HEAD ~ UES} once they have been used x number of {TAIL ~ times}  
The x ESDS displace both the DES and { HEAD ~ UES } once they have been used x number of { TAIL ~ times }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH