| Kind | Value | annotation | ||
| enumeration | 1_very early | |||
| enumeration | 2_very early to early | |||
| enumeration | 3_early | |||
| enumeration | 4_early to medium | |||
| enumeration | 5_medium | |||
| enumeration | 6_medium to late | |||
| enumeration | 7_late | |||
| enumeration | 8_late to very late | |||
| enumeration | 9_very late |