Currently they have none. Note that categories will need to be added to the "Season onset" target. From a discussion between @nickreich and @matthewcornell on 2020-12-13:
Recall that at one time I had coded splitting that target into two: 'Season onset binary' and 'Season onset date', but you decided to revert:
I think for now, it is best to stick with season onset as 1 nominal target (not the split binary/date as I had first thought). This target would have categories that would have YYYY-MM-DD strings as the categories (every Monday during the season) plus a "none" category.
Looking at the CDC Real-time Forecasts and CDC Retrospective Forecasts zoltar projects, I see that "Season onset" is indeed a nominal target, but it doesn't look like we followed through with the categories (there are no cats for that target).
Currently they have none. Note that categories will need to be added to the "Season onset" target. From a discussion between @nickreich and @matthewcornell on 2020-12-13: