Which resource is a formal computable definition of a graph of resources?

• A. GraphDefinition
• B. StructureDefinition
• C. CodeSystem
• D. StructureMap

Answer: (A)

GraphDefinition is the resource that provides a formal computable definition of a graph of resources. It specifies a starting resource and the edges that connect resources, describing how to traverse from one resource to related resources and which parts to include. This enables clients and servers to reason about and fetch related resources in a defined graph, such as pulling a Patient along with related Encounters, Observations, and Conditions in a single operation. StructureDefinition profiles a single resource’s structure, CodeSystem defines codes, and StructureMap handles transformations between structures, none of which describe a graph of resources.