Quarantine "yellow jack" but this was also a name for yellow fever, which probably derives its common name from the flag, not the color of the victims (cholera ships also used a yellow flag). The plain yellow flag ("Quebec" or Q in international maritime signal flags) probably derives its letter symbol for its initial use in "quarantine", but this flag in modern times indicates the opposite—a ship that declares itself free of quarantinable disease, and requests boarding and routine port inspection. Australia has perhaps the world's strictest quarantine standards. Quarantine in northern Australia is important because of its proximity to South-east
Flag of Australia Union Flag in the UK, when the House of Representatives proclaimed that the Blue Ensign "should be flown upon all forts, vessels, saluting places and public buildings of the Commonwealth upon all occasions when flags are used". The government agreed to fly the Blue Ensign on special flag days, but not if it meant additional expense, which undermined the motion. The Blue Ensign could only be flown on a state government building if a state flag was not available. On 2 June 1904 a resolution was passed by parliament to replace the Union Jack with the "Australian Flag" on forts.