Business transactions between companies are more and more executed by a flow of well-defined electronic business documents. The resulting inter-organizational business processes are often realized by concepts known from service-oriented computing. Exchanging a business document corresponds to a service call and the input/output of the service calls commonly follows a certain business document standard. However, these standards typically present the superset of all required elements used in any business context. In a specific context (in a specific industry, in a specific geopolitical region, etc.) the input/output is adjusted to this context by constraints on the generic structure. Accordingly, a specific service is always used in a specific context. It follows that it is important to define the business context of a service (in a structured format). For this purpose we have developed the Business Context Ontology model (BCOnt). In this paper we elaborate on the theoretical concepts and the underlying algorithms as well as on their implementation in practice.