Physical modeling enables you to produce models that can be easily reused and shared with other engineers. Importing data and models from other environments helps ensure the accuracy of your models. By integrating those models with control and signal processing algorithms, you can test for integration errors early in the design process. The logical model defines the business entities that will be rendered by the application and what policies and rules will be used to operate on those entities. The questions this model answers are very specific to the business for which you are writing your application.