The space of all design problems can be mapped on a plane where one axis extends from routine to non-routine problems and the other from parametric to conceptual as in figure 1.1.
Figure 1.1: The space of all design problems
These axis are continuous. There are no clear cut lines that differentiate problems into routine or non-routine, and parametric or conceptual. Still, the problems this work deals with can be loosely characterized as the ones in the lower left quadrant of this plane, routine parametric design problems.
Routineness of a design problem suggests that the knowledge and processes required to solve the problem are known and well understood [Brown & Chandrasekaran 92]. Being parametric means that the structure of the design and all parameters of it are known in advance, so that the design process has to deal with assigning a set of values to these parameters. The values should satisfy a set of constraints on the parameters. These constraints may arise from physical laws, some preferences, and user requirements.