How does anyone realize any feature of a package? It’s mentioned in the documentation! E.g., if it was a keyword firstprimary=true, it would be listed under “attributes” in the documentation.
Still, I’m not sure if the approach I implemented is the best. It covers what I usually want to do, but perhaps there might be cases where one want’s to apply other settings to the first of a number of series. My version only supports Bool. Maybe one want’s to apply similar logic to non-booleans, even though I couldn’t immediately think of a use case.