Acronyms that contain the term official letters 

official letters

All official letters which are intended to be laid before the commander-in-chief, must be signed by the officers themselves, specifying their rank under their signatures. All applications from petty officers, seamen, and marines, relative to transfer, discharge, or other subjects of a similar nature, are to be made through the captain or commanding officer. They ought to be written on foolscap paper, leaving a margin, to the left hand, of one-fourth of the breadth, and superscribed on the cover "On H. M. Service."

see more »