
Flag Semaphore - Stratoscope
https://en.wikipedia.org/wiki/Flag_semaphore
======
Stratoscope
A friend just told me that the peace sign came from the flag semaphore signals
for "N" and "D". I was skeptical, but she was right!

[https://en.wikipedia.org/wiki/Peace_symbols](https://en.wikipedia.org/wiki/Peace_symbols)

What intrigues me about the flag semaphore system isn't just the character
encoding, but the protocol:

> _The sender uses the "Attention" signal to request permission to begin a
> transmission. The receiver uses a "Ready to receive" signal not shown above
> to grant permission to begin the transmission. The receiver raises both
> flags vertical overhead and then drops them to the rest position, once only,
> to grant permission to send. The sender ends the transmission with the
> "Ready to receive" signal. The receiver can reply with the "Attention"
> signal. At this point, sender and receiver change places._

