18 CFR § 3a.91 - Data index system.

---
identifier: "/us/cfr/t18/s3a.91"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "18 CFR § 3a.91 - Data index system."
title_number: 18
title_name: "Conservation of Power and Water Resources"
section_number: "3a.91"
section_name: "Data index system."
chapter_name: "FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY"
subchapter_number: "A"
subchapter_name: "GENERAL RULES"
part_number: "3a"
part_name: "NATIONAL SECURITY INFORMATION"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "15 U.S.C. 717o; 16 U.S.C. 825h."
regulatory_source: "Order 470, 38 FR 5161, Feb. 26, 1973, unless otherwise noted."
cfr_part: "3a"
---


# 3a.91 Data index system.

A data index system shall be established for Top Secret, Secret, and Confidential information in selected categories prescribed by the Interagency Classification Review Committee, in accordance with section VII of the National Security Council Directive Governing the Classification, Downgrading, Declassification, and Safeguarding of National Security Information, May 17, 1972.