HL7 International.
URL: https://www.hl7.org/fhir/
Abstract. The definitive specification for the Fast Healthcare Interoperability Resources standard, providing technical guidance for modern health data exchange. FHIR R5, published March 2023, introduced improvements to subscriptions, workflow management, and clinical reasoning resources. However, FHIR R4 (2019) remains the most widely implemented version in production systems and the basis for US regulatory mandates under the 21st Century Cures Act.