(a) For actions that require EAs or EISs, NASA encourages programmatic-level analysis for actions that are similar in nature, broad in scope, or likely to have similar environmental effects. Programmatic NEPA analyses may take place in the form of an EA or EIS. (b) Tiering from previously prepared EISs or EAs is appropriate when it would eliminate repetitive discussions of the same issues and exclude from consideration issues already decided. Tiering from a programmatic-level NEPA document is appropriate for site- or project-specific actions that are included within the scope of the programmatic-level analysis.