evidence: What are classified documents? [...] A subset of Top Secret documents known as SCI, or sensitive compartmented information, is reserved for certain information derived from intelligence sources. Access to an SCI document can be even further restricted to a smaller group of people with specific security clearances. [...] Then, there may be extra security protocols involved in viewing Top Secret information. Some documents must be viewed in what’s known as a SCIF, or a sensitive compartmented information facility.