From which instruction should each Letter-Type Directive be assigned an SSIC number?

The correct answer is found in SECNAVINST 5210.11D, which outlines the Navy's directives and provides the system for assigning Standard Subject Identification Code (SSIC) numbers to various types of documents. This instruction specifically details how directives, including Letter-Type Directives, should be categorized and numbered, ensuring consistency and ease of reference across the Navy.

Assigning SSIC numbers helps maintain order and facilitates effective communication within the Navy. Each directive must be categorized appropriately for effective management and retrieval of information, which is reinforced by the guidelines set forth in SECNAVINST 5210.11D. This document serves as a crucial reference for personnel involved in the issuance and management of Navy directives, stressing the importance of correct SSIC assignment.

Other instructions, while pertinent to different areas of Navy operations and communications, do not specifically address the assignment of SSIC numbers to Letter-Type Directives as SECNAVINST 5210.11D does, which solidifies its relevance to the question.