No. | D/Ha | Location of PMCD | Crown shape |
1 | ≤0.4 | Multiple points | Cylindrical |
2 | 0.5 - 0.9 | Bottom | Conical |
3 | ≥1.0 | Middle | Spherical |
4 | 0.5 - 0.9 | Top | Inverted conical |