Ontological analyses have been used in numerous publications to compare existing modelling grammars with an ontology. However, a sound theoretical research framework is still missing. Consequently, working with the results of such ontological analyses is theoretically questionable. The aim of the paper is threefold. Firstly, we want to contribute to such a theoretical research framework by formalising the ontological analyses approach. Secondly, we derive four formal requirements each ontological analyses must comply with. Lastly, we analyse whether current state of the art ontological analyses comply with our findings. While the formalisation demonstrates the strengths of the approach we conclude that current ontological analyses have theoretical deficiencies, which lead to serious limitations in their application.