These are additional markings commonly used on classified material. The appropriate markings are placed on the front cover of a document or on the first page if there is no cover. The markings serve to notify and warn the holder of special requirements for protection of the information and must be prominently placed on documrents, on material itself, if feasible, or in accompanying documentation.
Graydon J. Gerber, Naval Ocean Systems Center (NOSC,) San Diego, California.
<a rel="nofollow" class="external text" href="http://www.dtic.mil/dtic/tr/fulltext/u2/a200314.pdf">Security Is Everybody’s Business</a> (Technical Document 490, Revision <i>B</i>,) page A-14.