Business document types exchanged between business partners significantly differ among different industries and geopolitical regions. Therefore, the corresponding documents must be based on business document standards which can be adapted to any business context specific business scenario. In order to use a business document standard in a specific context, user groups develop so-called implementation guidelines based on a small subset of the standard. However, defining a new implementation guideline for a specific business context always starts from scratch, which is time-consuming and often leads to heterogeneous interpretations of the standard. It is our goal to speed up this development process and to create more homogeneous implementation guidelines by learning from existing models. Therefore, in this paper we define an ontology based model to formally represent business context. Furthermore, we propose an approach to assign instances of this model to already existing document implementation guidelines. This serves as a basis for calculation of the content model (subset) of a new implementation guideline which is relevant in a particular context presented by our ontology based business context model.