ExperimentalOptional Readonly ExperimentalcountRow count behind the value, when it differs from value.
Readonly ExperimentalkeyReadonly ExperimentallabelReadonly ExperimentalmeasureOptional Readonly ExperimentaltargetsFeature targets this mark stands for, when the producer can enumerate them cheaply. Enables mark-click to drive map/table selection directly instead of only filtering.
Readonly ExperimentalvalueMeasured value. null means "no value" and must render as an explicit
gap — never as 0 — unless the null policy is counted-as-zero.
One scalar aggregate ("big number") value.