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