spread property
Spread is the distance between the highest and lowest of them, nil when there is only one. It is the disagreement AMONG sources, which a single Published number cannot show — signal in the same way the published-minus-measured gap is.
Please note: This property should have been non-nullable! Since the specification file does not include a default value (using the "default:" property), however, the generated source code must fall back to having a nullable type. Consider adding a "default:" property in the specification file to hide this note.
Implementation
num? spread;