The answer to yesterday’s data challenge: full-time, year-round workers can be unemployed, but only very briefly. 

You don’t have to actually work full-time to be a full-time worker.  “Full-time” workers can be unemployed indefinitely as long as they “usually worked 35 hours or more in a week.” 

Year-round employment status, in contrast, requires actually working year-round.  As this BLS release explains:

Year-round and part-year employment. Workers are classified as year round if they worked 50 to 52 weeks. Part-year employment refers to workers who worked fewer than 50 weeks.

In short, as soon as a year-round worker experiences more than two weeks of unemployment, he ceases to be a year-round worker.