Introduction to sets and mappings in modern economics.

The HWC Regulatory Interpretations Index is an invaluable, time-saving reference tool that gives you quick and easy access to listings of more than 28,000 pages of EPA regulatory interpretations in the form of OSWER directives and RDB memos. These documents are cross-referenced by CFR page/section, citation, and by subject keyword. The OSWER directives are documents used to identify and communicate policy and procedures by EPA regional offices. The documents identify new policies, clarify existing policies, specify procedural guidelines, and offer program guidance. Most of the RDB interpretations are short letters that explain EPA's position on various regulatory questions. Updated annually, The HWC Regulatory Interpretations Index makes it easy for you to obtain current documents pertaining to your situation, which ultimately makes it easier to Understand The RCRA regulations!