We just learned about the Charlie Flag.
Another of the maritime flags is the Delta Flag, used for the letter D.
This flag also means "Keep clear of me; I am maneuvering with difficulty."
![delta flag](https://upload.wikimedia.org/wikipedia/commons/thumb/e/eb/ICS_Delta.svg/480px-ICS_Delta.svg.png)
(from: wikipedia - international maritime signal flags)
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