Context We run medical-device manufacturing applications on Ignition 8.3. We maintain an ISA-95-based UDT library (with some domain-specific additions) in Git and deploy it to all gateways from Azure DevOps. New equipment gets the library's UDTs and publishes consistently to our UNS. Problem UDT definitions are shared by every project that uses the same tag provider. When a definition changes, every instance changes immediately, including instances used by validated applications that we cannot change without formal change control. In regulated environments this makes it hard to evolve a shared UDT library safely. Current workarounds (and why they fall short) Version in the tag path (e.g. .../Fiducial/V1.1/Fiducial1) Separate tag providers per UDT version Both result in different tag paths per version, duplicated data, and significant maintenance in each application and in the UNS. Deployment mode (8.3) covers part of the deployment story, but not the need to keep multiple definition versions side by side on the same gateway. Proposed feature Allow multiple versions of a UDT definition to exist side by side on the same gateway. Let a project (or gateway configuration file) pin which UDT library version it uses. Instances only receive definition changes when they explicitly opt in to a newer version. Tag paths stay stable regardless of which definition version is used. Ideally, definitions can be sourced from a Git-backed library in a text/diff-friendly format. Benefits Validated applications stay unchanged until they go through change control. One shared UDT library across all gateways without forking tag paths or providers. Clean, reviewable change history for UDTs in source control. Consistent UNS structure across versions. Ref: support ticket #199606