Abstract. Through a proof of concept in SWI-Prolog, this paper demonstrates a business transaction model by which the trading partners can derive their own, personal perspective from shared data. The demonstration is an innovative formalisation of the Resource-Event-Agent (REA) ontology as it allows for switching viewpoints in real-time between one trading-partner's perspective and that of a trading-partner with an opposing view (i.e., customer or supplier), or a trading-partner independent perspective (e.g. trusted third-party). The business transaction model is achieved by uniting REA with the Open-EDI Business Transaction Ontology (OeBTO). The resulting unified formalisation of the REA ontology (REA 2 ) also highlights implications for the future development of a) enterprise information systems (EIS) in the cloud, b) social-media-based EIS, c) blockchain EIS, and d) EIS interoperability across business paradigms. The EIS interoperability such as between traditional EIS (which typically uses a trading-partner perspective), and EIS for the collaborative economy (which typically uses a trading-partner independent perspective) is particularly highlighted as it becomes much more transparent than previously.