From Functional Specification to Concept Design - Strengths and Weaknesses in Some Current European Approaches

Most commercial computer aided design (CAD) is not really design software but instead either supports two dimensional drafting or three dimensional geometric modeling, with added text representing dimensions, tolerances, process notes, and so on. The most advanced commercial CAD software permits geometry to be parameterized by numerical or symbolic arguments, with some equality and inequality constraints on these variables. However, such software mainly supports creation of geometry at a detailed level and does not directly permit engineering, exploration of rough concepts, or discovery of conflicts and tradeoffs. When commercial CAD companies and their customers speak of "concept design," moreover, they usually mean exploration of geometric shapes, often rather creative shapes. In other cases they mean exploration of space allocation, typically involving packing components inside a given skin. [Brown]