The FHIR version must be consistent across the entire interaction, not just per resource.

• A. True
• B. False
• C. Sometimes
• D. It depends on resources

Answer: (B)

FHIR version refers to the version of the specification that defines how a resource is structured. Each resource in an exchange is validated against the version that defines its schema, and the server’s capabilities indicate which version it supports. The standard does not require every resource in a single interaction to come from the same FHIR version; in some architectures, different resources could come from different versioned contexts or servers. What matters is that each resource is compatible with the version it uses and that references between resources are resolvable within the given interaction. Therefore, the FHIR version does not have to be consistent across the entire interaction, only per the version-defining context of each resource.