Semantic marks

A descriptor's area treatment is solid, fade, hatch or dots; bars support solid, hatch and dots. Each series owns its paint and matching legend/tooltip key. status(row) explicitly marks observed, provisional or forecast readings. The last row is never guessed to be incomplete. series.curve accepts step-after and step-before to hold values on opposite sides of an exact transition. series.fields adds companion values in the series' unit, such as a range's ends, quartiles, or a candle's open, high and low. They fit the y axis and appear in hover; IntervalBand, RangeBar, ErrorBar, BoxPlot and Candles (from @lilt-ui/charts/finance) draw them by field ID. Lilt never infers them. series.colorAt(row) colors one bar, candle, range or point, and y.scale="log" spaces values by ratio.

Combine area.treatment="dots" or "hatch" with area.fade=true for texture that fades toward the baseline without changing the plotted values. RangeChartCard and BoxPlotCard wrap the range marks as finished cards.