Abstract
For over a decade now, a community of researchers has contributed to the ontological foundations of Conceptual Modeling by participating to the development of the Unified Foundational Ontology (UFO) and the UFO-based modeling language OntoUML, which have been successfully employed in a number of different sectors. The empirical feedback from these experiences led us to reconsider UFO’s theory of relations, proposing a new theory that has already been applied to model subtle notions in the business domain, such as value, risk, service, and contract. In this paper, we advance a first formal characterization of this new theory, which is then used to design a new metamodel for OntoUML.