The delta structures 200 have a lattice 210 of interconnected strands which intersect to define {HEAD ~ a plurality} of {TAIL ~ cells} 220 
The delta structures 200 have a lattice 210 of interconnected strands which intersect to define { HEAD ~ a plurality } of { TAIL ~ cells } 220
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH