Within this work, we model the semantics of the BPMN 2.0 standard as an ASM ground model. First, we want to provide a basis for identifying gaps, inconsistencies, and practical problems of the given standard and also for manipulating the semantics in order to overcome the identified problems. Secondly, the developed ground model is the basis for the construction of a CoreASM specification, which will allow to simulate BPMN models based on the given semantics and further variations as well as to assess the effects of particular provisions and their variations. Thirdly, we want to provide a basis for respective implementations.