33.2. Definition: Variation and Evolution Points
First, two points of change in a software system (first introduced in the Protected Variations pattern) are worth reiterating:
- variation point
Variations in the existing current system or requirements, such as the multiple tax calculator interfaces that must be supported. - evolution point
Speculative points of variation that may arise in the future, but which are not present in the existing requirements.
As will be seen, variation and evolution points are recurring key elements in architectural analysis.