The goal of the German project “Standardization of Communication between Information Systems in Physician Offices and Hospitals using XML” (aka SCIPHOX) in its first phase is to provide information exchange based on the Extended Markup Language XML between Hospital Information Systems (HIS) and Physician Office Systems (POS). The Clinical Document Architecture (CDA), a standard developed by the Health Level Seven organization (HL7), was chosen to serve as the “backbone” specification. The CDA is an ANSI approved document architecture for exchange of clinical information using XML. In phase I of the SCIPHOX project the proposal specifies the use of the CDA as a generalized international standard in the national context of discharge and referral letters in Germany. The specification defines how to use the CDA header and associated vocabularies by providing a translation and interpretation of the CDA header tags and provides a solution for taking local needs (insurance information etc.) into account.