[1] A letter-form which enables the sender to address his Seniors more abruptly than he would dare to do without its assistance.

[2] D.S.B. = Duty Steam Boat.

[3] A.I.O. = Admiralty Interim Order.

[4] K.R.A.I. = King's Regulations and Admiralty Instructions.

[5] C.P.O. = Chief Petty Officer.

[6] O.O.D.—Officer of the day.