  The term behavior engineering (BE) encompasses a broad integration of
behavioral and compositional requirements needed to model large-scale systems.
BE forms a connection between systems-engineering processes and
software-engineering processes. In software engineering, interpreting
requirements can be perceived as specifying behavior, which is viewed in terms
of chronology of events in the modeled system. In this paper, we adopt BE in
its general and integrating sense to search for a unifying notion of an event
as a fundamental behavior-modeling concept. We examine several bodies of
research with various definitions of an event and its basic units and
structure. We use the thinging machine (TM) model to analyze notions related to
events, including Dromey s behavior trees, fluents (change over time),
recurrent events, and Davidson s events. The results point to an underlying
meaning that can lead to a unifying event concept.
