Sensitive compartmented information (SCI) is a type of United States classified information concerning or derived from sensitive intelligence sources, methods, or analytical processes. All SCI must be handled within formal access control systems established by the Director of National Intelligence. SCI is not a classification; SCI clearance has sometimes been called "above Top Secret", but information at any classification level may exist within an SCI control system. When "decompartmentalized", this information is treated the same as collateral information at the same classification level. The federal government requires the SCI be processed, stored, used or discussed in a Sensitive compartmented information facility (SCIF).

Access

Eligibility for access to SCI is determined by a Single Scope Background Investigation (SSBI) or periodic reinvestigation. Because the same investigation is used to grant Top Secret security clearances, the two are often written together as TS//SCI. Eligibility alone does not confer access to any specific SCI material; it is simply a qualification. One must receive explicit permission to access an SCI control system or compartment. This process may include a polygraph or other approved investigative or adjudicative action. Once it is determined a person should have access to an SCI compartment, they sign a nondisclosure agreement, are "read in" or indoctrinated, and the fact of this access is recorded in a local access register or in a computer database. Upon termination from a particular compartment, the employee again signs the nondisclosure agreement.

Control systems

SCI is divided into control systems, which are further subdivided into compartments and sub-compartments. These systems and compartments are usually identified by a classified codeword. Several such codewords have been declassified. The following SCI control systems, with their abbreviations and compartments, are known:

Markings

SCI control system markings are placed immediately after the classification level markings in a banner line (banner spells out TOP SECRET in full) or portion marking (here TS is used). Sometimes, especially on older documents, they are stamped. The following banner line and portion marking describe a top secret document containing information from the notional SI-GAMMA 1234 subcompartment, the notional SI-MANSION compartment, and the notional TALENT KEYHOLE-BLUEFISH compartment (TK is always abbreviated, because in some cases even the full meaning may be classified, like for BUR keyword, BUR-BLG-HCAS, BUR-BLG-JETS): TOP SECRET//SI-G 1234-M/TK-BLFH//NOFORN (TS//SI-G 1234-M/TK-BLFH//NF) Older documents were marked with HANDLE VIA xxxx CONTROL CHANNELS (or "HVxCC"), HANDLE VIA xxxx CHANNELS ONLY (or "HVxCO"), or HANDLE VIA xxxx CHANNELS JOINTLY (or "HVxCJ"), but this requirement was rescinded in 2006. For example, COMINT documents were marked as HANDLE VIA COMINT CHANNELS ONLY. This marking led to the use of the caveat CCO (COMINT Channels Only) in portion markings, but CCO is also obsolete.