Which statement best describes the relationship between CUI and restricted data in an unclassified document?

• A. They must not be commingled; restricted data are classified.
• B. They can be mixed freely if needed.
• C. CUI is above restricted data in classification.
• D. CUI should replace restricted data in unclassified docs.

Answer: (A)

CUI and restricted data are treated as different protection levels. CUI is information that remains unclassified but requires controlled handling, labeling, and safeguarding. Restricted data, on the other hand, is information that is classified under the Atomic Energy Act and must be protected as classified material. Because of that, you should not mix them in an unclassified document—the presence of restricted data would raise the document’s classification status. If restricted data is involved, the document should be classified at the appropriate level (or the restricted content must be redacted or separated) rather than kept unclassified. This separation ensures legal and policy protections are correctly applied and prevents the leakage of classified information through unclassified materials.