(a) Proposed and Final Decisions (including dissenting opinions) and all orders made with respect thereto, except when exempted from public disclosure by statute;

(b) Statements of policy and interpretations which have been adopted by the Commission which have not been published in the Federal Register; and

(c) A current index, which will be updated at least quarterly, covering the foregoing material adopted, issued or promulgated after July 4, 1967. Publication of an index is deemed both unnecessary and impractical. However, copies of the index are available upon request for a fee of the direct cost of duplication.