Sensitive Compartmented Information (SCI) separation is identified primarily through markings called caveats or control markings, which are appended to classified information to denote specific compartments the material belongs to. These markings are used alongside classification levels (e.g., Top Secret, Secret) and serve to separate SCI from other classified information. SCI materials require controlled access, including security clearances (usually Top Secret plus SCI indoctrination) and need-to-know determinations. Key methods to identify the separation of SCI include:

• Markings on documents or materials with specific SCI caveats, often shown in the banner line (e.g., TS//SCI or TS//[compartment code]).
• Use of portion markings within documents to denote the classification and compartment of each part.
• Physical protection inside Sensitive Compartmented Information Facilities (SCIFs), with strict access controls such as badge checks and need-to-know verification.
• Special handling instructions requiring SCI materials to be stored, processed, and discussed only within authorized environments with cleared personnel.
• Formal indoctrination and signing of nondisclosure agreements to confirm authorized access.
• Distinct access registers or databases tracking who is cleared for which SCI compartments.

These measures collectively ensure that SCI is separated from other classified information and protected according to its sensitivity and compartmentalization requirements.