| 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 |