The notion of RDF Named Graphs has been proposed in order to assign provenance information to data described using RDF triples. In this paper, we argue that named graphs alone cannot capture provenance information in the presence of RDFS reasoning and updates. In order to address this problem, we introduce the notion of RDF/S Graphsets: a graphset is associated with a set of RDF named graphs and contain the triples that are jointly owned by the named graphs that constitute the graphset. We formalize the notions of RDF named graphs and RDF/S graphsets and propose query and update languages that can be used to handle provenance information for RDF/S graphs taking into account RDFS semantics.