| Kind | Value | annotation | ||
| enumeration | 1_very sparse | |||
| enumeration | 2_very sparse to sparse | |||
| enumeration | 3_sparse | |||
| enumeration | 4_sparse to medium | |||
| enumeration | 5_medium | |||
| enumeration | 6_medium to dense | |||
| enumeration | 7_dense | |||
| enumeration | 8_dense to very dense | |||
| enumeration | 9_ very dense |