More preferably, {TAIL ~ each} of the tags includes first identity data defining a relative position of that tag, and second identity data identifying {HEAD ~ the surface} 
More preferably , { TAIL ~ each } of the tags includes first identity data defining a relative position of that tag , and second identity data identifying { HEAD ~ the surface }
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD