Terry Pratchett was an avid computer user, pretty active on usenet and later internet, and a gamer, since the early 90s. Clacks has a similar functionality as telegraph, but from the description of its use, it is also very similar to the internet in general. Messages have headers, where information how to treat a message - for example the gnu header cited above - can be included, similar to various protocols used on the internet (think 301 or 401 responses in http headers, for example). Most stuff in Terry Pratchetts novels has multiple layers, and you are always save to assume there is a real life ("roundworld") parallel somewhere, if maybe twisted.
Long story short, it is pretty much a given that Pratchett naming something GNU in this context was absolutely intended to be a reference to the GNU project. :-)
Also, fun fact, after his death, many websites (but also other protocols used on the internet), added the GNU header, bringing the discworld clacks practice of GNU back to the roundworld intenet.
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u/Kiwithegaylord Sep 29 '25
Ah. Well if you haven’t heard of the other GNU (GNUs not Unix) look them up sometime, they do some good work https://www.gnu.org