Event-driven Process Chains (EPCs) have been helped to achieve an important role in business process modeling by the commercial success of SAP and ARIS. Both users and IT experts may describe the process to be modelled from their individual perspectives. Event-driven Process Chains, therefore, create a common platform for communication and the analysis of ideas beyond the boundaries of both application and information-system domains. This is accomplished by a semiformal semantics, which gives the participants greater freedom of expression but leads to unintended ambiguities clearly undesirable in later stages of development such as design and implementation. In the literature, several approaches to this problem have been suggested including definitions of a formal semantics for EPCs. We investigate difficulties with such approaches and suggest two solutions: the introduction of a new logical connector (XORAND) and a slight modification of the OR join. This facilitates the design of correct EPCs while continuing to allow freedom of expression, thus enabling a smoother transition into the more formal phases of software development such as design and implementation. A comparative experiment validates these results.