This Technical Report covers aspects of federations of Clinical Document Registries (CDRs) including cases

where the whole content of a CDR has been replicated in another CDR of the same federation. More specifically,

the following aspects are covered.

a) Recommendations for the creation and management of federations of CDRs and federation metadata.

b) Creation and management of federated replicas, including specifications to create, remove and maintain

federated replicas as well as metadata for them.

c) Use cases of federations with query processing examples, including various use cases of federations of

CDRs, together with examples of query processing policies to enhance the performance and fault-tolerance.

d) Processing of queries in the presence of federations and replicas: the presence of federated replicas might

affect the semantics of both local and federated queries. Informative examples to define exact behaviours

of processing the queries are given.

NOTE It is assumed that the problem of patient identification has been solved in a way that is beyond the scope of

this Technical Report, such as IHE XCPD (Cross-Community Patient Discovery) Profile. Some potential issues that will

not be addressed in this Technical Report include patient identity management, potential limitations of registries due to

jurisdictional policies or requirements, and how replicates are handled.