32 CFR 2001.25: Declassification markings.
A uniform security classification system requires that standard markings be applied to declassified information. Except in extraordinary circumstances, or as approved by the Director of ISOO, the marking of declassified information shall not deviate from the following prescribed formats. If declassification markings cannot be affixed to specific information or materials, the originator shall provide holders or recipients of the information with written instructions for marking the information. Markings shall be uniformly and conspicuously applied to leave no doubt about the declassified status of the information and who authorized the declassification.
(b) The following markings shall be applied to records, or copies of records, regardless of media:
(1) The word, “Declassified;”
(2) The identity of the declassification authority, by name and position, or by personal identifier, or the title and date of the declassification guide. If the identity of the declassification authority must be protected, a personal identifier may be used or the information may be retained in agency files.
(3) The date of declassification; and
(4) The overall classification markings that appear on the cover page or first page shall be lined with an “X” or straight line. An example might appear as:
Declassified by David Smith, Chief, Division 5, August 17, 2008