| Value | Category |
|---|---|
| 0 | Not completed grade 1 |
| 1 | Grade 1 |
| 2 | Grade 2 |
| 3 | Grade 3 |
| 4 | Grade 4 |
| 5 | Grade 5 |
| 6 | Grade 6 |
| 7 | Grade 7 |
| 11 | Form 1 |
| 12 | Form 2 |
| 13 | Form 3 |
| 14 | Form 4 |
| 15 | Form 5 |
| 16 | Form 6 |
| 20 | Diploma/certificate after prim. |
| 21 | Diploma/certificate after sec. |
| 22 | Graduate/postgraduate |
| Sysmiss |