We just learned about the Delta Flag.
Another of the maritimes is the Echo Flag, used for the letter E.
It is blue and red, and also means "I am altering my course to starboard."
![echo flag](https://upload.wikimedia.org/wikipedia/commons/thumb/0/0b/ICS_Echo.svg/480px-ICS_Echo.svg.png)
(from: wikipedia - international maritime signal flags)
Kid Facts - Blast from the past: Computer Keyboard