Decisions in the course of definition hundreds of part, part placing, analysis, control program and other related entities during development of a product in a modeling system are done using less or more information and knowledge in the background. One of the most actual problems to be solved in product modeling is including this background information and knowledge in the model. If this capability of model representation for background would be available, it could drive processes for entity definition and redefinition of entities at their changes, and would help engineer at understanding decisions of other engineers. The authors of this paper proposed a content based product model where human defined knowledge for product objects definition. In this paper, they introduce a method for the application of this content as background for decisions. Paper explains the concept of background at product object definition. Following this, background is characterized as it is considered at decision on product objects. Next, engineering process entities are explained for considering background during the above decisions. Finally, few words outline possibilities for implementation and future research.