ReadonlyduesOne passed due date per late task, so the count of late tasks is this list's length. A task with several passed dates contributes the earliest that parses, else a stored value as written.
ReadonlykindReadonlytaskSet exactly when one task is late — with more, no single title stands for the mark.
How late the run is, listed per late task. The mark shows a shared span only when every late task shares that span.