With the increasing complexity of designs, Design Data Management is regarded as a key enabling technology to achieve higher efficiency in the development of complex products. However, this technology has proven to be surprisingly complex. Commercial solutions in the area of CAD Frameworks, Product Data Management, and Configuration Management Systems currently only solve parts of the total problem, and the acceptance of these systems in industry is still relatively low. In this paper, a model is presented which can be used as a frame of reference for the general problem of managing design data. The model distinguishes between five orthogonal dimensions, which are each, when considered separately, quite simple. In practice, however, two or more dimensions must be handled simultaneously to solve real-world problems. This turns out to be nontrivial because multiple fundamentally different solutions exist for each combination of two or more dimensions. We believe that this 5-D frame of reference can contribute to the creation of better quality solutions in the area of Design Data Management. The 5-D model can also help to explain the familiar phenomenon that a solution which has, for example, proven to be adequate for software development may be rejected by integrated circuit designers, and vice versa.