While the results of scientific research have their own intrinsic value, access to these results is of crucial importance for the research process in general. To this end, the Dublin Core Initiative has suggested and detailed the concept of metadata, and international standards start to emerge for the different branches of science. The level of these standards, though, differs widely: while the definition and granularity of a set of metadata for electronic theses is fairly advanced, for general electronic documents these concepts are only in the early stage of development. Methods of common retrieval have to take these differences into account; thus we use the term of a horizontal approach for a wide and interdisciplinary search, while we call a more detailed subject specific search a vertical approach. The Open Archive Initiative (OAI) and the MathDiss International project represent these different procedures. OAI ad-dresses distributed repositories: these sources can be identified and their metadata collected by service providers. This allows for scalable archives of arbitrary size of possibly interdisciplinary and international scope. For this the granularity of the metadata used has to be rather low, stressing the breadth of information instead. On the other hand, the concept of a subject specific document server with a central structure uses indexes of electronic resources created according to the rules of the field. These metadata are clearly specified and very detailed and thus allow for a very precise retrieval. The aim of the international activities should be to increase the mutual compatibility of these two developments and combine their respective strengths. This leads to the following central questions: * How can subject specific document servers be integrated in the Open Archive? * How do different fields differ in their schemes in collecting and serving information? * Semantics and user habits depend on the scientific field and have to be taken into consideration in new interdisciplinary concepts.