This European Standard series is intended as a guidance for the description, planning and development of new systems as well as for the integration of existing information systems - within one enterprise and across different healthcare organizations - through an architecture integrating the common data and business logic into a specific architectural layer (that is the middleware), distinct from individual applications and accessible throughout the whole information system through corresponding services. The overall architecture is formalized according to the criteria of ISO/IEC 10746 and is therefore structured through the following three viewpoints: a) The enterprise viewpoint which specifies a set of fundamental common requirements at enterprise level with respect to the organizational purposes, scopes and policies that must be supported by the information and functionality of the middleware. It also provides guidance on how one individual enterprise (for example, a regional healthcare authority, a large hospital or any other organization where this model is applicable) can specify and document additional specific business requirements, with a view to achieving a complete specification, adequate for the characteristics of that enterprise. b) The information viewpoint which specifies the fundamental semantics of the information model to be implemented by the middleware to integrate the common enterprise data and to support the enterprise requirements formalized in the enterprise viewpoint. It also provides guidance on how one individual enterprise can extend the standard model with additional concepts needed to support local requirements in terms of information to be put in common. c) The computational viewpoint which specifies the scope and characteristics of the services that must be provided by the middleware for allowing access to the common data as well as the execution of the business logic supporting the enterprise processes identified in the information viewpoint and in the enterprise viewpoint. It also provides guidance on how one individual enterprise can specify additional services needed to support local specific requirements in terms of common business logic to be implemented. The standard does not implicitly nor explicitly refer to a special technical solution or a certain product and has been prepared independently from such a product. Due to this, formalization of architecture, according to the two lower levels of the ODP reference model, the technical and technological views, is not included in the scope of this standard. The language and notation used for description of the architecture are based on UML (Unified Modelling Language), supplemented by case studies and other paradigms which are frequently used in other standards of health informatics. The description level is complete and clear enough to allow for its implementation according to specific physical and technological scenarios of various healthcare organizations and offerers. For such an application it is recommended to follow the methodology formalized by the technical and technological views of the ISO-ODP reference model. The standard is subdivided into three parts: - Part 1 (this part) describes the overall characteristics of the architecture, formalizes the specification methodology and the conformance criteria, and provides details of the enterprise viewpoint of the architecture; Part 2 describes the information viewpoint of the architecture; - Part 3 describes the computational viewpoint of the service architecture. All documents are self-contained and can also be used independently of each other for the intended purpose for different users (whereby Part 1 is directed at the management, Part 2 and Part 3 focus rather on design activities). Nevertheless, it should always be assumed that they represent three aspects of the same architecture. Therefore, reciprocal references exist between the different parts of the standard; developments which are based on the individual documents should follow the defined methodology in order to ensure overlapping integrity and consistency of the specification. The Committee responsible for this standard is NA 063-07-02 AA "Interoperabilität" ("Interoperability") at DIN.