Waterfall
Follow signed changes from an opening balance to the final result.
Use a waterfall to explain an ordered balance change. Deltas, checkpoint subtotals and the total are calculated by one flow; a view window never restarts accumulation.
Use one series in category order. A delta has type: delta and finite value; subtotal and total points have no value field. Null is rejected because an unknown change makes the balance unknown.
Configure rise, fall, total and connector colours, point labels, references, legend and viewport. Subtotals use changes since the previous checkpoint; total uses the accumulated balance including startValue. Vertical layout only; stacking is incompatible.