These past 15 months, sitting in our respective home offices, Slack has become our primary company telegraph, and it got us thinking about long distance systems of the past, such as the Flag Signal Code. So we made a slack version of the code. We’ve been having fun “running up” various communiquées using these and now you can as well. In addition to the signal flags, we made solid-color flags of the rainbow, and ones with letters on them.
Flag Signal Code key is here.