Indonesia: status in employment(class of workers)

Comparing the variables IND and CLASSWK of Indonesian data between 1980 to 2010,
I realized the number of observation for NIU(not in universe) is perfectly aligned EXCEPT FOR 2010:

IDN(2010) []

Since IDN and CLASSWK assume the same universe and CLASSWK is from a follow-up question of IDN, the exceptional discrepancy in 2010 does not seem very intuitive.

Can I know why there is such a difference only in the 2010 sample?

My apologies for the delay in response. It took a bit of time to figure out the source of the discrepancy.

In 2010, a number of people who were not employed or temporarily away from a job (unexpectedly) have valid values for CLASSWK. All of these additional responses are persons who are self-employed, and categorized under the “own account, with temporary/unpaid help” in the detailed version of the variable. These persons are out of universe for IND, as expected.