While current metamodelling languages are well-suited for the structural definition of abstract syntax and metamodelling platforms like the Eclipse Modelling Framework (EMF) provide various means for the specification of a textual or graphical concrete syntax, techniques for the specification of model semantics are not as matured. Therefore, we propose the application of reference attribute grammars (RAGs) to alleviate the lack of support for formal semantics specification in metamodelling. We contribute the conceptual foundations to integrate metamodelling languages and RAGs, and present
– a tool for the specification of EMF metamodel semantics using JastAdd RAGs. The presented approach is exemplified by an integrated metamodelling example. Its advantages, disadvantages and limitations are discussed and related to metamodelling, attribute grammars (AGs) and other approaches for metamodel semantics.