| Value | Category |
|---|---|
| 00 | None or less than basic |
| 10 | Basic (primary, 8 grades) |
| 20 | Secondary |
| 21 | Secondary, lower and middle vocational |
| 22 | Secondary, general, technical, professional |
| 30 | Higher education |
| 31 | Higher education, vocational and technical |
| 32 | Undergraduate |
| 33 | Graduate |
| 98 | Unknown |
| 99 | NIU (not in universe) |