A new version of SDL called SDL-2000 is currently reaching maturity, and is expected to pass the standardization bodies shortly. It will offer new features as object-oriented data types, simplify and unify concepts of previous language versions and provide an alignment with UML. Due to the significant changes to SDL it was necessary to define a new formal semantics for SDL. Abstract State Machines (ASMs) have been chosen as the underlying formalism. In this paper, after introducing the new SDL language features, it is shown, how these features get an executable formal semantics using ASMs.