| Value | Category |
|---|---|
| 0 | Pre-school |
| 1 | STD 1 |
| 2 | STD 2 |
| 3 | STD 3 |
| 4 | STD 4 |
| 5 | STD 5 |
| 6 | STD 6 |
| 7 | STD 7 |
| 8 | STD 8 |
| 9 | Form 1 |
| 10 | Form 2 |
| 11 | Form 3 |
| 12 | Form 4 |
| 13 | Form 5 |
| 14 | Form 6 |
| 15 | Univ 1 |
| 16 | Univ 2 |
| 17 | Univ 3 |
| 18 | Univ 4 |
| 19 | Univ 5 and above |
| 20 | College |
| 21 | None |
| 22 | Others |
| 99 | Not stated |