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Note that the OpenMRS SHR will NOT participate in the Patient Identity Feed transactions (ITI-8, ITI-44) when performing transactions in the Document Registry role. In the wider OpenHIE architecture, the Interoperability Layer performs the task of resolving patient identifiers from the Client Registry (acting as Patient Identity Source) before sending transactions to the Shared Health Record. Therefore, the combination of the SHR and IOL provides a complete implementation of an XDS Registry. In addition, the SHR will also not provide the ITI-42 Register Document Set.b transaction functionality, which will be provided by the IOL whenever a Provide and Register Document Set.b transaction is received.
See this page: http://wiki.ihe.net/index.php?title=Cross_Enterprise_Document_Sharing as well as the technical framework documentation at http://www.ihe.net/Technical_Frameworks/#IT for technical details about the XDS.b transactions.