Sensitive security information
Sensitive security information (SSI) is a category of United States sensitive but unclassified information obtained or developed in the conduct of security activities, the public disclosure of which would constitute an unwarranted invasion of privacy, reveal trade secrets or privileged or confidential information, or be detrimental to the security of transportation. It is not a form of classification under Executive Order 12958 as amended.
Source: Wikipedia — Sensitive security information (CC BY-SA 4.0)