Bridging the Terminology Divide: From Community Vision to Technical Implementation in Healthcare

Healthcare interoperability increasingly depends on three major open standards—openEHR for clinical persistence, HL7 FHIR for real-time exchange, and OMOP for longitudinal analytics. While community consensus points toward open terminology APIs as transformative infrastructure, each standard has evolved fundamentally different approaches to managing external terminologies: openEHR constrains terminologies to fit archetype models (reductionist), FHIR augments them through extensions (extensionist), and OMOP maps them to a unified vocabulary layer (normalization). This paper argues that the path forward requires not a single unified terminology server, but an ecosystem of validated APIs capable of bridging these philosophical differences while preserving each standard's integrity. Drawing on experience across HL7 Vulcan, N3C, OHDSI, and multi-site research networks, the author proposes a meta-interoperability framework and calls for coordinated investment in distributed terminology infrastructure.