Media containing CUI is marked with distribution limitations.
Mark media with necessary CUI markings and distribution limitations.
The term security marking refers to the application or use of human-readable security attributes. System media includes digital and non-digital media. Marking of system media reflects applicable federal laws, Executive Orders, directives, policies, and regulations. See [NARA MARK].  The implementation of this requirement is per marking guidance in [32 CFR 2002] and [NARA CUI]. Standard Form (SF) 902 (approximate size 2.125” x 1.25”) and SF 903 (approximate size 2.125” x .625”) can be used on media that contains CUI such as hard drives, or USB devices. Both forms are available from https://www.gsaadvantage.gov.