| Code | Definition | Number of Accessions |
| 1 | upper smooth, lower smooth | 9 |
| 2 | upper smooth, lower sparse | 13 |
| 3 | upper smooth, lower dense | 1 |
| 4 | upper sparse, lower smooth | 5 |
| 5 | upper sparse, lower sparse | 55 |
| 6 | upper sparse, lower dense | 116 |
| 8 | upper dense, lower sparse | 2 |
| 9 | upper dense, lower dense | 112 |