In a data contract, what is the role of validation rules?

• A. They define authentication methods.
• B. They enforce field formats, required vs optional, and error semantics to ensure data quality.
• C. They determine service-level agreements.
• D. They handle caching strategies.

Answer: (B)

Validation rules define what valid data looks like in a data contract. They enforce field formats, indicate whether a field is required or optional, and specify how errors should be reported when validation fails, all to ensure data quality and predictable processing across services. For example, a contract might require an email field to be present and to match a proper email pattern, and a date field to follow a specific ISO format. When data violates these constraints, the system can return consistent error information, guiding the client to correct and resend. These rules focus on data validity, not on identity verification, performance guarantees, or caching strategies.