Final answer:
All elements of a message-type directive are based on the standard instructions provided by SECNAV M-5216.5, the Department of the Navy Correspondence Manual.
Step-by-step explanation:
All elements of a message-type directive are prepared per standard instructions for regular messages per SECNAV M-5216.5, which is the Department of the Navy Correspondence Manual. This manual outlines the policies and procedures for the preparation of correspondence within the Department of the Navy. When preparing a message-type directive, it's crucial to follow the guidelines stated in this document to ensure proper format, content, and distribution.