Occupational unit - vn_occ
1 = 1. Office chief
2 = 2. Factory chief
3 = 3. State finance, economics, and planning
4 = 4. Technical staff
5 = 5. Agricultures staff
6 = 6. Science education
7 = 7. Art culture
8 = 8. Medical science
9 = 9. Law
10 = 10. Secretary, clerk
11 = 11. Energy
12 = 12. Mining
13 = 13. Metallurgy
14 = 14. Electronic, mechanics
15 = 15. Chemical industry
16 = 16. Paper industry
17 = 17. Building glass mater
18 = 18. Wood industry
19 = 19. Printing publishing
20 = 20. Weaving industry
21 = 21. Clothing industry
22 = 22. Leather wool
23 = 23. Food
24 = 24. Building
25 = 25. Agriculture
26 = 26. Forestry
27 = 27. Fishing
28 = 28. Transport
29 = 29. Tele communication
30 = 30. Dockers carriers
31 = 31. Seller supplier
32 = 32. Public service
33 = 33. Others
98 = 98. Unknown
99 = 99. NIU (not in universe)