Classification Frameworks

U.S. Government Executive Order Classification (EO 13526)

• TOP SECRET (TS): Unauthorized disclosure could cause exceptionally grave damage to national security.
• SECRET (S): Unauthorized disclosure could cause serious damage to national security.
• CONFIDENTIAL (C): Unauthorized disclosure could cause damage to national security.
• UNCLASSIFIED (U): No damage to national security; publicly releasable.

Atomic Energy Act / Nuclear Classifications (AEA 1954)

These run parallel to and can override EO classifications for nuclear weapons information:

• Restricted Data (RD): Covers nuclear weapon design, production, and material. Cannot be declassified by executive order alone — requires AEC/DOE action.
• Formerly Restricted Data (FRD): Nuclear-related military information that has been jointly declassified by DOE and DoD but retains special handling.

Sensitive Compartmented Information (SCI)

Applied on top of a base classification level (usually TS) to restrict access to specific intelligence programs or sources:

• TS/SCI: Top Secret with a specific compartment designation (e.g., HCS, SI, TK). Requires a separate “read-in” beyond a standard clearance.

Special Access Programs (SAP)

• Acknowledged SAP: Existence of the program is publicly known; details are classified.
• Unacknowledged SAP: Existence of the program itself is classified (sometimes called “black programs”).
• Waived SAP: Congressional oversight is limited to a small number of senior members, the most restricted category.

Control Markings & Dissemination Controls (CAPCO)

These are not classification levels themselves but restrict who can see a document regardless of clearance:

• NOFORN (NF): Not releasable to foreign nationals.
• REL TO [country]: Releasable to specified allied nations.
• ORCON: Originator controls dissemination.
• PROPIN: Proprietary information involved.
• FOUO / CUI: For Official Use Only / Controlled Unclassified Information — below the classified threshold but restricted from public release.

NATO Classification Levels

• COSMIC TOP SECRET (CTS)
• NATO SECRET (NS)
• NATO CONFIDENTIAL (NC)
• NATO RESTRICTED (NR)
• NATO UNCLASSIFIED (NU)

Declassification Mechanisms

• Automatic Declassification: Most records are automatically declassified after 25 years under EO 13526, unless exempted.
• Systematic Review: Agencies review older documents for declassification on a schedule.
• Mandatory Declassification Review (MDR): Requested by individuals; agency must review within set timelines.
• FOIA Declassification: Courts can compel review, but cannot compel declassification of genuinely sensitive material.

In the context of the nuclear testing documents relevant to your research (e.g., SWEH-2-0034, DNA-6005F), you will typically see layered markings such as “SECRET//RESTRICTED DATA//NOFORN” on original documents — with individual paragraphs sometimes marked at lower levels (e.g., (U) or (S//RD)) in a practice called portion marking.