The Föderal system is a flexible repository for the management, integration and modeling of product data. Current systems in this domain employ object-oriented data models. Whereas this is adequate for the management of product data, it proves insufficient for integration and modeling. Present semistructured data models, however, are suited ideally for integration, but data management and also modeling is a problem. In this paper we describe our approach to narrow down the gap between structured and semistructured data models. We present the Föderal information system which employs a new semistructured data model and show how this model can be employed in the context of management, integration, and modeling of engineering data.