COVAX (Contemporary Culture Virtual Archive in XML) is an 1ST (Information Society Technology) funded project, launched as part of the 1ST first call, corresponding to key action 3 (Multimedia content and tools: cultural heritage and digital content) in the action line 111.2.3 (Access to scientific and cultural heritage) under the European Community Fifth Framework for research and development. The main objective of COVAX is to test the use of XML to combine document descriptions and digitised surrogates of cultural documents to build a global system for search and retrieval, increasing accessibility via the Internet to electronic resources, regardless of their location. The project duration is 24 months. It started in January 2000 and the partners include content owners (memory institutions) and technological partners (developers: public RTD centres and private companies). CO VAX's approach to achieving its objectives is based on the conversion of existing records to homogeneously-encoded document descriptions of bibliographic records, archive finding aids, museum records and catalogues, and electronic texts and on the application of XML (eXtensible Markup Language) and the various Document Type Definitions (DTDs) currently being used for library resource descriptions (MARC DTD), archives finding aids (EAD), museum materials (AMICO DTD) and electronic versions of cultural texts (TEllite). COVAX is designed to form a network of XML repositories as a distributed database. This will be accessed as a single database and will act as a mets-search engine, offering access to book references, finding aids, facsimile images, museum items, and other resources. COVAX is constructing a multilingual user interface to access such data. The project does not intend to create standards but to rely on the adoption of existing standards and concepts (XML, DTDs already in use, http...), using the Z39.50 protocol as a conceptual basis for communication between the multilingual user interface and the meta-search engine and Dublin Core Metadata Element Set elements as cross-domain access points. The conversion process has proved to be a crucial one in the CO VAX-project and we therefore try to concentrate, in this article, on questions concerning our experiences of converting mainly library catalogues of different MARC or proprietary formats to XML.