Standardized business documents are a prerequisite for Electronic Data Interchange (EDI). One predominant standards family are the Electronic Data Interchange For Administration, Commerce and Transport (EDIFACT) formats created and maintained by the United Nations Centre for Trade Facilitation and Electronic Business. However, EDIFACT formats are currently specified in a textual manner where semantic relationships between data elements are neither formally nor explicitly described. While these relationships are usually easy to identify for humans, this information is hidden to machines. This hampers semantically accurate interpretation of EDIFACT messages. In addressing this shortcoming, we present an approach for conceptualizing EDIFACT messages in ontologies, the EDIonto approach. Thereby, we provide means for modeling and storing both structural information acquired from the official EDIFACT standards as well as semantic information about the relationships between data elements. Furthermore, we describe means for storing concrete EDIFACT messages in knowledge bases according to the developed ontologies. We evaluated our approach by comparing it to state-of-the-art tools for interpreting EDIFACT messages. Contrary to the other tools, the approach presented in this paper allows for the automated and semantically accurate processing of generic EDIFACT messages.