Defense Security Service

Defense Security Service Guide to Marking Classified Information

This guide gives Department of Defense (DoD) staff and contractors an overview of the kinds of marking required to protect classified and unclassified controlled information that cannot be disseminated to all audiences. The guide offers an integrated approach to the major requirements for marking and control of information, briefly explaining the reasons for marking and providing examples of correctly marked information. To facilitate information sharing and declassification processes, whenever practicable a classified attachment, addendum, annex, enclosure, or similar section shall be used when classified information constitutes only a small portion of an otherwise unclassified document.