  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.
