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 Greece ensign Greek Orthodox merchants (better: merchants from the Greek-dominated Orthodox "millet") were allowed to fly on their ships, combining stripes with red (for the Ottoman Empire) and blue (for Orthodoxy) colours. After the Treaty of Küçük Kaynarca, Greek-owned merchant ships could also fly the Russian flag. During the uprising of 1769 the historic blue cross on white field was used again by key military leaders who used it all the way to the revolution of 1821. It became the most popular Revolution flag, and it was argued that it should become the national flag. The "reverse" arrangement, white cross on