In {HEAD ~ a polygonal rib structure} having {TAIL ~ ribs} directed orthogonal to one plane and intersecting each other to form polygonal shapes, a thickened central portion located at a substantially central portion in the longitudinal direction of each side of the polygonal rib is bisected 
having
In { HEAD ~ a polygonal rib structure } having { TAIL ~ ribs } directed orthogonal to one plane and intersecting each other to form polygonal shapes , a thickened central portion located at a substantially central portion in the longitudinal direction of each side of the polygonal rib is bisected
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL 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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH