The SanteDB Clinical Data Repository (CDR) is designed for large-scale regional/national digital health applications. Solutions running on SanteDB may be deployed in dozens, hundreds or even thousands of clinics across a widespread region. In these scenarios, there will be times where individual clinics or points of service will lose connectivity, and this is especially true in geographically sparse and/or low resource environments. SanteDB was designed from the ground up to support this highly distributed scenario and is equipped with a robust synchronization engine that allows individual clinics to go online and offline as they require, while still allowing users to continue to work in their applications without being uninterrupted and without losing any clinical data. When clinics are able to re-establish connectivity, all transactions are synchronized seamlessly between local data stores and the central repository. Each remotely deployed application instance (for example in a clinic, mobile, or anywhere "out on the field") maintains a local version of SanteDB referred to as the distributed clinical data repository or "dCDR". The main central clinical data repository is referred to as the integrated clinical data repository or "iCDR". There is no predefined limit as to how long dCDR apps are able to work offline before they reconnect with the iCDR.