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