Please note the explanations on page 4 of the household list.
16. You practice your profession as:
[] Unpaid family worker
[] Employee, civil servant
Worker, namely:
[] Semi-skilled worker, unskilled worker
[] Apprentice
For Question 16, do you practice your profession as: Workers mark "Skilled worker" or "Semi-skilled worker, unskilled worker", as the case may be, if they are classified in their business.