What does N/A code mean for tranwork variable

If the universe is persons age 16+ who worked last week what does the “N/A” code mean for “tranwork” variable?

The discussion on this question may be helpful. Basically, “N/A” indicates that the question does not apply to that specific individual. As the universe statement of the TRANTIME variable suggests, respondents need to be (a) 16 years old or older and (b) working outside of their home last week to be eligible for this question. So, those marked as “N/A” do not meet these criteria.