FHIR (Fast Healthcare Interoperability Resources) and HL7 materials
An overview of FHIR - https://www.hl7.org/fhir/overview.html
Jump off point for everything FHIR - http://wiki.hl7.org/index.php?title=FHIR
FHIR compared to openEHR - https://wolandscat.net/2017/01/29/fhir-compared-to-openehr/