NARA MARK

National Archives and Records Administration (2016) Marking Controlled Unclassified Information, Version 1.1. (National Archives, Washington, DC).

https://www.archives.gov/files/cui/20161206-cui-marking-handbook-v1-1.pdf

CUI Notice 2019-01, Controlled Unclassified Information Coversheets and Labels.

https://www.archives.gov/files/cui/documents/20190222-cui-notice-2019-01coversheet-label.pdf