Xenon: An RDF Stylesheet Ontology
information to bear from diverse sources t o automate tedious processes for the user is a key tenet of th e Semantic Web vision. In previous papers we argued that visualizi ng semantically-connected corpora is not only a prime example of one of these processes but is also a critical probl em that must be solved to gain acceptance from the broader community as to the benefits of RDF. In this paper we elaborate on the specific topic of ontologies for describing how resources should b e presented to the user. We propose the creation of an RDF stylesh eet language, reusing many of the key ideas of the XSL Transformations language (XSLT), but incorporating the requirement that when multiple ontologies are used in the description of a resource to be presented, multiple stylesheets, potentially from d ifferent authors, will need to be composed. This notion of enabling heterogeneous composition motivates the definition of our basic building blo ck concepts of view and lens. In addition to abstractly characterizing our notion of an RDF stylesheet, we also describe o ur concrete instantiation of these ideas in the Xenon ontology. Finally, we give a concrete example illustrating how our styles heet mechanisms enable developers to easily produce both HTML- based and custom rich client-based browsers for het erogeneous datasets.