Without common semantic definitions, there is no guarantee that senders and receives will interpret content in the same way. As such definitions are not provided by DTD's or schemas, they have to be defined in external databases, such as tag repositories. Without such repositories, no standardisation of messages or documents will be really possible. In the described German project, the semantic content of a repository using the xDT proprietary standard is transferred into an XML repository and is used to establish XML messages for the communication between physicians offices and hospital information systems. Problems of generalisation and specialisations will be described. The repository will be available on the Internet to improve and speed up the maintenance of the repository and to give the user continuous access to the newest versions. First experiences with this approach will be described and demonstrated.