Today, there exists a huge variety of business document models for electronic data exchange among business partners used in business-to-business, business-to-government, as well as government-to-government business transactions. Thus, it becomes inevitable to process differing document models in daily business, unless a commonly agreed standard is developed. However, even if a commonly agreed standard exists, a multitude of different document definitions will still be existent in the short-term. Incompatibilities between old document formats and the newly introduced document models are the consequence. To cope with various document models and formats we propose a heuristic approach that leverages interoperability by mapping common document models to the conceptual Core Components model introduced by UN/CEFACT. To successfully complete this mapping task we define a set of rules that may be applied to XML Schema based document models.