This annex represents input to the TOPS as a framework to eventually compare and rate different technologies. This "attributes" framework is still in development. Additional work will help refine many of the discussions and ratings of the specific barriers to proliferation, enhancing the utility of the framework. In some cases, further work will allow a broader range of distinctions to be made in the degree of proliferation barriers posed by the features of a nuclear system. At the present stage of development, this framework cannot be used to quantitatively score or rank technologies. Also, in lacking a system to estimate the weights of various attributes, this framework is limited to comparisons of the effectiveness of each attribute among civilian nuclear power systems and proliferation threat scenarios.