The measure.
Lower end of the dial.
Upper end of the dial.
OptionallabelWhat the measure is called, when the chart names it.
OptionaltargetThe target marker a bullet chart draws, when it has one.
OptionalbandsQualitative bands, in ascending order.
A gauge or bullet chart: one measure against a range.
Unlike every other trace's data this is a single object rather than an array, because the chart draws exactly one measure -- the same reason HeatmapData is an object. An array of one would describe a shape the chart does not have.
The value alone is not the reading. "73" means nothing without the range it sits in, the target it was aiming at, and the band it lands in, and none of those are written anywhere a screen reader can reach on a drawn gauge.