A web service choreography standard enables a standardized description of business processes that allows not only a clear specification of the control flow, but also forms the basis for the actual process execution. Such standards are part of the web services stack and facilitate enterprise systems interoperability. A simple indication of the rapid growth of this area is the number of new and existing standards. However, while the list of standards is expanding, there is an obvious lack of sound theoretical evaluation and comparison of these standards. To provide a basis for this theoretical evaluation and comparison, we use the well-established Bunge–Wand–Weber (BWW) models, in particular the representation model. We, and other researchers, have shown the usefulness of the BWW representation model for analyzing, evaluating, and engineering techniques in the areas of traditional and structured systems analysis, object-oriented modeling, and process modeling. In this paper, we present the BWW ontological analysis of four dominating candidate interoperability standards; ebXML Business Process Specification Schema BPSS (v1.01), the Business Process Modeling Language BPML (v1.0), the Business Process Execution Language for Web Services BPEL4WS (v1.1) and the Web Service Choreography Interface WSCI (v.1.0). The application of the BWW representation model and the overlap analysis across the four standards has resulted in several interesting findings. First, we have identified a set of ontological constructs for which representations are missing in each of the standards. This situation has allowed us to generate a number of propositions as to the potential weaknesses of the standards in general. Second, the analysis has shown that ebXML BPSS is a “clear winner” with respect to the ontological expressiveness and the maturity of the specification. Furthermore, the analysis has also allowed us to identify two sets of standards viz. ebXML BPSS and BPEL4WS, ebXML BPSS and WSCI, that, when used together, provide the user with the largest available set of meaningful constructs required to implement systems interoperability. Finally, the analysis explains which standards are complementary to each other and which standards are in fact competing standards.