define producer and consumer data contracts and schema evolution rules, covering field set types and nullability, the semantics a schema cannot carry such as units timezone currency null meaning and enum meaning, compatibility mode and the enforcement point that actually rejects a violation, breakin
define producer and consumer data contracts and schema evolution rules, covering field set types and nullability, the semantics a schema cannot carry such as units timezone currency null meaning and enum meaning, compatibility mode and the enforcement point that actually rejects a violation, breaking change policy, deprecation windows, versioning and coexistence, and the contracts that are only im