Today there exist many important applications in business and commerce that consist of millions of lines of code that are becoming increasingly difficult to maintain. These applications have been written in one of early third generation languages, that has evolved over a long period of time and they are under continuous modification for business reasons. Such applications are classified as a legacy application. It is often very expensive to add new customer-demanded features to this code and to adapt it to ever-changing hardware specifications. This problem is exacerbated by the fact that the original authors of the code are often not available and the huge code base exists with little or no documentation.