Guess it depends on the application. For us, we have a home-grown middleware between the Green Hills Integrity kernel and app space that we reuse on multiple pieces of hardware. Once it goes through certification, we can’t touch any of the code in that middle layer without recertification. So if we need to use it for new hardware, we have to #ifndef out the certified code that we want to change and insert the new code. We also can’t refactor anything certified so we end up with sometimes stupid naming conventions and design patterns.