Abstract. In this short paper we describe the DFL hybrid knowledge base, that integrates descriptions with expressive object-oriented rules. The knowledge base manages a database of explicit descriptions and facts, by consulting two separate reasoners: DL { The Description Languages reasoner, and R { The Rules reasoner. The architecture generalizes all existing hybrids of descriptions and rules. DFL, is provided with a compositional semantics, given as a collection of syntactic objects, that allows the reasoners to operate under di erent semantical policies. The compositional semantics respects the modularity of its components, Its declarative semantics is de ned using F-Logic ( 8]) as an underlying semantics, and is consistent with the (sometimes only operational) semantics of existing hybrids. The current ongoing implementation re-implements a description reasoner and a rule reasoner that manage a shared database. The implementation is discussed, and results are presented.