A foundation for action

The systematic evaluation of one or more parameters through equations, charts, algorithms, simulations, prototype evaluations, or review of data. 

An item, data, or document has been submitted to and reviewed by an authority and that authority has made a determination and communicated that it is acceptable 

The set of fundamental concepts or properties of a system in its environment, embodied in its elements, relationships, and the principles of its design, operation, and evolution.