Feature modeling is a standard method in the field of domain engineering to determine the extent of software reuse. Applying this method results in a feature diagram and an accompanying description about the mandatory and variable aspects of the software system in question. It is this classification and relationship of these relevant aspects that ultimately determine the degree of reuse.  A practical exercise in applying feature modeling would be to study a widely used, commercially available software system such as the Oracle 9i database server. The resulting feature model can give the required insight on the flexibility and capability of Oracle 9i, where it comes to evaluating it as a viable product based on client needs.  Modeling the Oracle 9i database server involves starting with the feature model of a general database model and then adding or refining features that are specific to Oracle. To do this, sources of documentation are consulted to ascertain the capabilities of each feature. The wealth of information collected from these sources is then evaluated for proper integration into the feature model.  The feature model presented here is one of many possible models that can exist for Oracle 9i. This model's intent is to show the range of its capabilities but other ones can be formulated based on a specific area of concentration or interpretation.