Over time in the Discworld novels, the inhabitants of the Disc came up with a long-distance communications method called “the clacks” – a cross between the telegraph and semaphore. Initially they’re only used in Anhk-Morpork, and mostly by the Watch, but soon there are towers all across the land conveying messages between cities and countries.
In Going Postal we learn that the clacks have something called “overhead”, meta-data, of sorts, for the messages being sent, not unlike the header data contained in emails or web pages which doesn’t appear on the screen, but which contains important instructions on how the page should be displayed. When one character questions the presence of a name in the overhead, another tells her it is the name of an operator who was killed. A code is transmitted with his name, ensuring that it will always be sent on to the next tower, for “A man’s not dead while his name is still spoken”.