I think you're kind of mixing up version or release numbers there. HL7 has several major standards: V2 Messaging, V3 (including CDA), and FHIR. And each of those has gone through multiple releases. FHIR was on R4 for a couple years and R5 was recently published.

Yeah, I’m doing that thing where I speak sloppily. HL7 is the standards organization, so talking about “HL7 messages” is like talking about “ISO messages”. It’s a misnomer.

But as someone at the sharp end of the stick wrt integrations? If I hear someone talk to me about HL7 I’m thinking HL7v2, and if someone says FHIR I’m thinking US Core v2 + FHIR R4. That just seems to be lingua franca.

Ah that makes more sense.