| Value | Category |
|---|---|
| 0 | don't know |
| 1 | managerial, executive and high administrative |
| 2 | independent professional |
| 3 | middle and lower salaried professional |
| 4 | inspectoral and semi-professional |
| 5 | clerical and non-counter sales |
| 6 | skilled manual |
| 7 | routine white collar and counter sales |
| 8 | semi-skilled |
| 9 | unskilled |
| 10 | none |
| 11 | other |