Final answer:
A naval directive is an authoritative instruction in naval letter format that sets policies or commands action, deriving from constitutionally granted powers, including the President's role as Commander in Chief.
Step-by-step explanation:
A directive that is prepared in naval letter format and establishes policy or orders specific action is known as a naval directive. These directives are authoritative instructions or commands from a higher level within the naval hierarchy. The purpose of a naval directive is to set policies, delineate responsibilities, or provide detailed instructions to enforce discipline and ensure the effective operation of the Navy. Such directives derive authority from various parts of the Constitution, which outline the powers to provide and maintain a Navy, and to make Rules for the Government and Regulation of the land and naval Forces. Moreover, Article II of the Constitution designates the President as the Commander in Chief of the Army and Navy, granting the office the power to issue orders and require written opinions from executive officers on subjects related to their duties.