In a series of publications, we have proposed a foundational system of ontological categories which has been successfully used to evaluate and improve the quality of conceptual modeling grammars and models. In this article, we continue this work by using this foundational ontology to provide real-world semantics and sound modeling guidelines for one of the most fundamental (and yet one of the most problematic) constructs in conceptual modeling, namely, the relationship type. In addition, we systematically compare our approach with a classical ontological treatment of this construct in the literature, provided by the BWW framework.