Da Vinci Payer Data Exchange (PDex, hl7.fhir.us.davinci-pdex) defines how payers expose a member's health history as US Core-shaped clinical FHIR: payer→provider (CDS Hooks + SMART), payer→payer (member-authorized), and payer→third-party app (Patient Access API). Recent STU versions also profile ExplanationOfBenefit to share prior authorization status — part of the CMS-0057 Prior Auth / Access API payload shape.

Division of labor worth memorizing: CARIN Blue Button is the claims/financial view (EOB); PDex is the clinical view plus prior-auth sharing; US Core is the profile floor. PDex also makes member vs. subscriber vs. dependent terminology explicit — the same ID semantics that trip up test data and coverage registries.

What ImOnFHIR does with it: core comply-track content for Access and prior-auth APIs. Validator packages stay pinned to published PDex versions (watch CI for STU bumps); our synthetic member/coverage projections stay conscious of PDex ID semantics. We point at the open IG — we do not host licensed CPT or proprietary payer code systems that sometimes appear in real EOBs.