On the other hand, TeX has a logo, as you can see in this 1988 article by Knuth. https://tug.org/TUGboat/Articles/tb07-2/tb15knutlogo.pdf https://tug.org/TUGboa

On the other hand, TeX has a logo, as you can see in this 1988 article by Knuth. https://tug.org/TUGboat/Articles/tb07-2/tb15knutlogo.pdf https://tug.org/TUGboat/Articles/tb07-2/tb15knutlogo.pdf > Logos are trademarks of companies At least in the US, that's incorrect. Private persons people may hold trademarks too. That trademark my be registered with the federal or state government, but even without registration there's still a common law trademark. If you start selling artisan lemonade from your sidewalk (make sure you have the proper licenses first!) and make a distinctive logo for it, then - poof! - that logo is a common law trademark. No paperwork needed. Even if it's the trademark is not enforced, it's still a logo. A 5th grade sports team can decide to call themselves "The Flying Stone", make a design with a stone bearing wings, and put it on their shirts. Poof, that's a logo. > national flags aren't language logos ... why would they? The US doesn't have an official language. Many countries have multiple official languages. Most languages don't have a strong association with a single country. And Esperanto has had a flag for over a century, representing supranational solidarity.