What document provides comprehensive guidance on identifying and marking classified documents?

The Marking Classified National Security Information booklet provides essential guidance on the identification and proper marking of classified documents. Its purpose is to ensure that individuals handling classified materials understand how to correctly apply and interpret classification markings according to established protocols. This document outlines the necessary symbols, notices, and procedures that are critical to maintaining the security of classified information.

The other options, while they may relate to security and classification, do not specifically focus on the guidelines for marking classified documents. For example, the Security Classification User Guide may provide broader information on classification processes but does not serve as a primary resource for marking. Similarly, the Classification Management Manual and the National Security Document Guidelines may address comprehensive procedures for managing classified information but do not center specifically on the marking aspect as the Marking Classified National Security Information booklet does. This focus on marking is crucial for compliance with security regulations and for safeguarding national security interests.