For entities, it is straightforward what this referential world is.
compared to entities, events are less tangible (Guarino, 1999; for various reasons: 1. we use a small vocabulary to name events, which results in large referential ambiguity 2. events are more open to interpretation and framing, which leads to more variation in making reference 3. events are less persistent in time than entities 4. each event has many idiosyncratic properties, e.g.