A complete example BM_000 BM_111 67 BM_222 33 0.5 BM_xxx 75 BM_yyy 20 BM_zzz 5 1.5 BM_aaa 60 BM_bbb 30 BM_ccc 6 BM_ddd 4 20 Primary Road BM_ASPHALT 0.15 BM_SAND 90 BM_ROCK-GRAVEL 10 0.55 Painted Dry Wall BM_PAINT BM_DRYWALL 0.015 Runway Concrete BM_CONCRETE 0.26 BM_SAND 0.66 Driveway Pavement BM_PAINT-ASPHALT BM_ASPHALT 0.10 BM_SAND 0.15 The simplest composite material BM_ xyz