The Marine Register in Minor Records shows the cause of death as a number. What does this mean?

The Marine Register records deaths of Royal Navy and Royal Marine personnel during wartime including members of the Royal Naval Reserve, the Royal Naval Volunteer Reserve and the RNLI.
Cause of death was recorded in the register as a number (1, 2, 3 or 4), defined as follows:

Key to Codes in the Marine Register relating to Royal Navy and Royal Marine War Deaths:

Code 1

• Killed in action.
• Died of wounds or disease following wounds.
• Missing after action and subsequently presumed killed in action.
• Killed, Died of wounds or exposure, Died of disease following wounds or exposure, Drowned, Missing and subsequently presumed killed or drowned following loss of ship in action, by mine or torpedo.

Code 2

• Killed, Died of injuries or exposure, Died of disease following injuries or exposure, Drowned, Missing and subsequently presumed killed or drowned following the accidental loss of a ship (wreck, collision, internal explosion, etc.) or where actual cause of a vessels loss is not known.
• Accidental deaths (killed, drowned, etc).
• Deaths due to injuries or disease following injuries accidentally sustained.

Code 3

• Deaths from disease.

Code 4

• Deaths due to Suicide, Murder, Alcoholism, Heat Stroke.
• Deaths under Anaesthetic.
• Any cases which cannot be classified under disease or accident.