Which type of resource identifies two or more records that refer to the same real-world occurrence?

• A. MessageHeader
• B. Linkage
• C. OperationOutcome
• D. Parameters

Answer: (B)

Linkage is the resource type designed to identify two or more records that refer to the same real-world occurrence. It lets systems declare that separate resources — such as two Patient records or the same event captured in different systems — actually pertain to the same entity, aiding deduplication and reconciliation across data. The linkage resource groups those references and uses items with a type to describe how the resources relate (for example, which one is the source or whether a resource is an alternate representation). In contrast, MessageHeader, OperationOutcome, and Parameters serve different roles: message metadata, operation results or issues, and parameter values for operations, none of which identify duplicates across records.