We describe a relative-timed semantic model for Business Process Modelling Notation (BPMN). We define the semantics in the language of Communicating Sequential Processes (CSP). This model augments our earlier untimed process semantics by introducing the notion of relative-time in the form of delays and durations over non-deterministic ranges. By using CSP as the common semantic domain, we show some properties relating the timed and untimed model based on CSP's existing refinement orderings.
