32 C.F.R. § 2001.20 General [1.6].
Title 32 - National Defense
A uniform security classification system requires that standard markings be applied to classified information. Except in extraordinary circumstances, or as approved by the Director of ISOO, the marking of classified information created after September 22, 2003, shall not deviate from the following prescribed formats. If markings cannot be affixed to specific classified information or materials, the originator shall provide holders or recipients of the information with written instructions for protecting the information. Markings shall be uniformly and conspicuously applied to leave no doubt about the classified status of the information, the level of protection required, and the duration of classification.
Title 32: National Defense
PART 2001—CLASSIFIED NATIONAL SECURITY INFORMATION
Subpart B—Identification and Markings
§ 2001.20 General [1.6].
