Which resource type provides additional rules that constrain the optionality, cardinality, terminology bindings, data types, and extensions defined in the resources by an implementation?

• A. StructureDefinition
• B. CapabilityStatement
• C. Bundle
• D. Observation

Answer: (A)

StructureDefinition is used to create profiles that constrain how resources are used in a particular implementation. By defining a StructureDefinition, you specify exact rules for a resource's content: how many times an element can appear (cardinality), whether an element is optional or required (optionality), which data types an element may use, and which terminology bindings (value sets) apply to elements. It also governs extensions, allowing you to define additional elements or constrain existing ones. These constraints are captured in the profile so every system interpreting the resource follows the same rules, ensuring consistent data exchange across implementations.

Other resources don’t serve this role: a CapabilityStatement describes what a server can do, a Bundle is just a container for exchanging multiple resources, and Observation is a specific resource type used to record data rather than a mechanism to impose cross-implementation constraints.