Commission
From WikiPOBia
An officer's commission is the document issued to him by the Admiralty each time he is promoted or assigned to a new ship or station. In our period, a commission was printed on parchment from an engraved plate, with the recipient's name, that of his ship, and the date filled in by hand; it was signed on behalf of the Admiralty by the First Secretary and three members of the Board, and it usually bore a note of the date of his promotion to his current rank to serve as a reminder of his seniority. A new commission had to be drawn up each time an officer was moved from one ship or posting to another, even where there was no change in rank; this procedure was a relic of the early seventeenth century, when there was no professional officer class within the Royal Navy and its officers were simply gentlemen of a martial turn whose field of action happened to lie at sea. Thus an active sea-officer would accumulate a considerable number of commissions during his career.
Only lieutenants, commanders, post captains and admirals were appointed by commission.