The International Code of Signals flags were developed back in 1857 are still in use. Body signals for communication with foreign ships, if you can not express himself in their language or, for example, when out of service other means of communication.
As a rule, only one Flag signal can be raised. The flag should be raised up until a response is received from the host ship. So before you hang on the yellow truselya spreaders, think about what it could mean.
We use the boxes as a decoration, but with their help you can also encrypt the hidden message.