Documents that provide detailed operational guidance and notification of changes to, or clarification of, existing policies or requirements to the National Industrial Security Operating Manual (NISPOM) are known as what?

• A. Industrial Security Letter (ISL)
• B. Security Directive
• C. Policy Bulletin
• D. Security Memorandum

Answer: (A)

Industrial Security Letter is the vehicle used to provide detailed operational guidance and notify or clarify changes to the NISPOM. It translates broad NISPOM requirements into practical steps, examples, and interpretations that security offices and cleared contractors can implement, ensuring everyone knows how to apply updates in day-to-day operations. Other documents serve different purposes or broader mandates, so they aren’t the standard channel for the kind of detailed guidance and change notifications described.