The Safe Numerics library is implemented in terms of some more fundamental software components described here. It is not necessary to know about these components to use the library. The information has been included to help those who want to understand how the library works so they can extend it, correct bugs in it, or understand it's limitations. These components are also interesting in their own right. They are not dependent upon anything in the Safe Numerics library. Rather it's the other way around. The Safe Numerics library depends upon these components. It is thought that they may be useful outside of the context of the Safe Numerics library. For all these reasons, they are documented here.