The [Solution design of a target digital public service] is a view that defines the technological architecture of the service. It outlines the components of the service, how they will be integrated, and how they will communicate with each other. The solution design also includes a description of the service user interface (UI) and a plan for testing and deployment. A documentation of an existing digital public service is a similar document, but it focuses on the current state of the service. It includes a description of the service's functionality, the technical infrastructure that supports it, and the processes that are involved in delivering the service. Both types of documents are important for ensuring that digital public services are interoperable, which means that they can exchange data and work together seamlessly. The European Interoperability Reference Architecture (EIRA) is a set of guidelines that can be used to develop interoperable digital public services.