In the context of business process modelling, the Business Process Model and Notation (BPMN) is a de-facto standard with more than 70 commercial tools that currently support its use. Amongst its main modelling constructs, BPMN includes activities and events. However, the focus of the standard is on providing an intuitive graphical language, rather than formal semantics specifications. This results in semantic ambiguities regarding the interpretation of its modelling constructs. We investigate whether the main building blocks of BPMN commit to an ontological theory of the domain entities at hand, eventually clarifying this commitment by the approach of ontological analysis.