What must be given to all classified correspondence created by an activity?

All classified correspondence created by an activity must be assigned a serial number. This requirement is crucial for maintaining proper control and accountability over classified materials. A serial number serves as a unique identifier that allows for easy tracking, retrieval, and management of classified documents. It helps ensure that all classified information is documented correctly, enabling personnel to maintain organization and compliance with security regulations.

The use of serial numbers in classified correspondence is also important for audits and inspections, as it provides a clear record of the documents that have been created, received, or circulated. This systemized approach mitigates the risk of unauthorized access or mishandling, which could compromise sensitive information.

In contrast, while tracking numbers, file numbers, and reference numbers serve various purposes in correspondence management and organization, they do not replace the specific requirement for a serial number when dealing with classified correspondence. Keeping accurate records with serial numbers is essential for security protocols within the Marine Corps.