The exchange of semantically consistent service descriptions is an important issue for flexible integration facilities for electronic commerce. Currently there is a lack of semantic consistency on the Web, burdening arbitrary market relationships. Several standardization initiatives have addressed this issue before, but nonetheless, the setup and maintenance costs have been too high. Furthermore, too rigorous standardization is not appropriate. As tourism markets are particularly heterogeneous, there is a high demand for flexible, but consistent data schemes for distributed service descriptions on the Web. A mediated tourism market could solve the integration problem by providing global data schemes that are individually extendable. In this paper we propose an approach based on the Resource Description Framework (RDF) and eXtensible Markup Language (XML) Namespaces, which are promising technologies that could be used for addressing the interoperability issues, which remain, however, hard problems.