Designing software for customization and evolution

Writing software for several similar situations often involves writing a general purpose program for the domain, followed by customization appropriate for each situation. As domain understanding evolves, the general purpose program also evolves, leading to complications for the customized versions. The solution lies with the domain analysts and designers of the original system: they must characterize those domain aspects that require customization and those that are likely to evolve, and they must select design techniques that support both types of change