Software product lines have proved to be a successful and efficient means for managing the development of software in industry. The significant benefits over traditional software architectures have the potential to convince software companies to adopt the product line approach for their existing products. In that case, the question arises how to best convert the existing products into a softwar...

I.1. Physical motivation. From [St]: consider a function T (x) as representing the value of a physical variable at a particular point x in space. Is this a realistic thing to do? What can you measure? Suppose T (x) represents temperature at a point x in a room. You can measure the temperature with a thermometer, placing the bulb at the point x. Unlike the point, the bulb has nonzero size, so wh...