Synchronization of diverging versions of a controlled medical terminology

To share clinical data and to build interoperable computer systems that permit data entry, data retrieval, and data analysis, users and systems at multiple sites need a shared clinical terminology. However, local sites that adopt a shared terminology have local needs that prompt local-terminology maintainers to make changes to the local version. Meanwhile, maintainers of the shared terminology make changes to the shared version, and the two terminologies diverge. I propose a formal model for managing change, with additional features included for the local site. If terminology maintainers follow such a model, the local-terminology maintainer can synchronize the local version with the shared version at periodic intervals. I am implementing a prototype, which I will use to assess the model and to study the synchronization process.