| Value | Category |
|---|---|
| 00 | NIU (not in universe) |
| 10 | Primary or no formal education |
| 20 | Some secondary |
| 21 | Lower secondary |
| 22 | Upper secondary |
| 30 | Some vocational |
| 40 | Some tertiary |
| 41 | Third level, non-degree qualification |
| 42 | Third level, degree or higher qualification |
| 99 | Unknown |