| Value | Category |
|---|---|
| 0 | pre-school/none |
| 1 | primary 1 |
| 2 | primary 2 |
| 3 | primary 3 |
| 4 | primary 4 |
| 5 | primary 5 |
| 6 | primary 6 |
| 7 | primary 7 |
| 8 | secondary form 1 |
| 9 | secondary form 2 |
| 10 | secondary form 3 |
| 11 | secondary form 4 |
| 12 | secondary form 5 |
| 13 | secondary form 6 |
| 14 | university |
| 15 | after primary |
| 16 | after secondary |
| 17 | technical |
| 18 | adult education |
| Sysmiss |