Modelling language is the most known and visible part of a model editor as it defines the syntax of the symbols to be used, the graphical notation how they appear on the diagram and the semantics describing the meaning behind the symbols.
ADOxx realises the meta model approach as an implementation concept, which means that you have to inherit your concepts from the already predefined ADOxx meta model. This requires that you learn how to deal with the ADOxx meta model, but enables you to instantly use all the functionality provided by the meta model.
Hence the implementation of modelling language becomes quick and easy once you've understood the predefined ADOxx meta model.