One datum in a chart: a human-readable label, a numeric value, and the color used to draw it.
The same type backs bars, pie / donut slices, and legend rows so callers can reuse a single data model across every chart flavour.
fill colour for this datum's bar / slice / legend swatch.
caption shown under a bar or in a legend row.
magnitude; bars scale to the largest value in the set and pie / donut slices to the share of the total. Negative values are treated as 0 because a negative bar or slice has no meaningful geometry.
0