OPNAV Instruction
Introduction An '''OPNAVINST''' or '''OPNAV Instruction''' is a formally documented lawful order that is issued by the Chief of Naval Operations. These instructions are typically used to establish United States Navy policy, procedures, and requirements. The instructions are issued in the form of a memorandum on official Department of the Navy letterhead. Each instruction is referenced with an OPNAVINST directive number and a date. Typically, when a new instruction supersedes a previous instruction, a cancellation notice citing the prior OPNAVINST number is included.
References For a list of OPNAV Instructions you can refer to the  Department of the Navy Issuances website.This article is a generalization of hundreds of OPNAV Instructions that have been issued. For specific examples, see below:*  OPNAVINST 3591.1E SMALL ARMS TRAINING AND QUALIFICATION*  OPNAVINST 4790.4E SHIPS' MAINTENANCE AND MATERIAL MANAGEMENT (3-M) SYSTEM POLICY*  OPNAVINST 5100.23 NAVY SAFETY AND OCCUPATIONAL HEALTH (SOH) PROGRAM MANUAL*  OPNAVINST 5750.12 ANNUAL COMMAND OPERATION REPORT