About the Signal
X-Clacks-Overhead is a non-standardised HTTP header based upon the fictional work of the late, great, Sir Terry Pratchett.
In Terry Pratchett's science-fantasy Discworld series, "The Clacks" is a network infrastructure of Semaphore Towers, that operate in a similar fashion to telegraph - named "Clacks" because of the clicking sound the system makes as signals send.
In Sir Terry's novel "Going Postal", the story explains that the inventor of the Clacks - a man named Robert Dearheart, lost his only son in a suspicious workplace accident, and in order to keep the memory of his son alive, he transmitted his son's name as a special operational signal through the Clacks to forever preserve his memory:
GNU John Dearheart
G: Send the message onto the next Clacks Tower.
N: Do not log the message.
U: At the end of the line, return the message.
The nature of the 'GNU' code would keep the name of his son forever transmitting through The Clacks network so long as the network still existed.
"A man is not dead while his name is still spoken."
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