If the problems are unrelated, then there's no way they would interact right? Having the same variable wouldn't affect the working in any ways, the user can even do 'sometemporaryname = MovingRefFrame.global_time' to avoid confusion. But I get the point you are trying to make. I am just not sure putting time in the initialiser is a good idea. IF the user puts different variables for time in the same 'world' it could cause some problems.