An understandable concrete syntax and a comprehensible abstract syntax are two central aspects of defining a modeling language. Both representations of a language significantly overlap in their structure and also information, but may also differ in parts of the information. To avoid discrepancies and problems while handling the language, concrete and abstract syntax need to be consistently defined. This will become an even bigger problem, when domain specific languages will become used to a larger extent. In this paper we present an extended grammar format that avoids redundancy between concrete and abstract syntax by allowing an integrated definition of both for textual modeling languages. For an amendment of the usability of the abstract syntax it furthermore integrates meta-modeling concepts like associations and inheritance into a well-understood grammar-based approach. This forms a sound foundation for an extensible grammar and therefore language definition.