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 China flag. For a medium detachment, a modified flag is used. The flag has a length of 60 centimetres and a width of 80 centimetres. A 20-centimeter triangle is cut out of the fly edge of the flag and the golden emblem is shifted closer towards the hoist. The customs flag is a China's national flag with the emblem of customs at the lower right corner, which consists of a golden key and the Caduceus of Hermes, crossing with each other. The current customs flag was officially adopted in 1 October 1953. The customs flag should be hung at the bow