The Resource-Event-Agent (REA) ontology is a powerful and well accepted approach towards the design of enterprise information systems in the academic world. However, it still lacks application in industry products. Software like ERP applications might benefit from REA data structure by building their product’s core on a robust, economic theory based, business ontology. Consequently, we have lately started a feasibility study with an Austrian ERP vendor, in which we investigate whether or not the ERP vendor can use the REA ontology as basis for their new ERP system. This paper is aimed at raising questions about uncertainties in REA we came across in our study so far.