Final answer:
The size of the Post flag can vary, with national flags usually measuring around 107.3 x 153.8 cm. The flag is flown to represent national or regional pride, commemorate events, or communicate messages.
Step-by-step explanation:
The size of the Post flag varies depending on its purpose and location. In general, national flags, like the American flag, are approximately 107.3 x 153.8 cm in size, as seen in figures 6.6.15 and 4.6.15. However, there are also larger flags, like the Country Post flag mentioned in figures 3.10.21 and 5.10.21, which are 182.88 x 411.48 cm in size.
As for when the Post flag is flown, it is typically raised to represent national or regional pride, commemorate significant events, or signal important messages. For example, national flags are often flown on official holidays, during sporting events, or at government buildings. The specific occasions and guidelines for flying flags can vary between countries and regions.