A database model which provides a unique level of support for engineering design and manufacturing is proposed. Engineering design applications have very different data management requirements than general business applications, e.g., handling several different kinds of data efficiently: graphics, and solid geometries as well as traditiona record-oriented data. Modeling several different views of component hierarchies. Modeling alternative versions of designs. Modeling the partial consistency which is characteristic of evolving designs. The data proposed is object-based not record or tuple based, and is highly extensible. A key element in extensibility is the distinction drawn between the specification of a type and its representation, allowing custom representations to be defined for different types of data: 2d and 3d graphics, geometry, solids models, matrix-based analysis/simulation data, cartographic data, digitized images, text, and voice -- representations which are highly efficient for these types of data.
