Alternatively, the data can be stored in fixed locations and {TAIL ~ the portals} moved from {HEAD ~ location} to location 
Alternatively , the data can be stored in fixed locations and { TAIL ~ the portals } moved from { HEAD ~ location } to location
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH