To properly fit into an Enterprise Architecture, we need to support the idea of external (e.g. national) registries of Patient, Location, Provider, Concept, and probably other metadata.
Our (evolving) design for providers will support this (by allowing lightweight storage of provider stubs) but we should investigate whether other domain objects might need to evolve to support this.
We will also need a mechanism to support mapping our local metadata to codes from an external registry.
(I'm initially putting this ticket in 1.9. I would expect it, or parts of it, to be bumped to a later version.)