The RDF Schema Specification Revisited

In this paper, we will discuss the proposed recommendation (March 1999) for an RDF Schema Specification and compare the approach taken in this specification to conventional meta data models. We will point out several pecularities in the RDF schema specification compared to more conventional approaches, which are basically due to the dual role of properties such as subclass and domain both as primitive constructs used in the definition of the RDF schema specification and as specific instances of RDF properties. We then discuss an approach for specifying RDF schemas, which distinguishes between a set of specific properties, which are needed in the RDF meta model itself, and conventional properties. Finally we show how we use this modified RDF meta model in a structured hypertext system (the KBS Hyperbook System), which uses RDF annotations not only for informational purposes, but also for structuring hypertext according to the semantic relationships recorded by these RDF annotations.