[tex-k] Is TeX in the public domain?

[Karl Berry]

Is TeX in the public domain? Answer: yes.

Sigh. Did you think you were bringing up a "bug" that was actually new?

It is true there are inconsistencies in what Knuth has written in
various places at various times about "licensing". However, his ultimate
intent is and always has been clear, namely the public domain status of
the programs, with the additional wish (not enforced via copyright) that
a program "shouldn't" call itself "TeX" unless it meets his stated
critera.

The copyright statements in the book are definitive. There is also
https://tug.org/TUGboat/tb11-4/tb30knut.pdf (linked on the TL copying
page), with the statement "I have put these systems into the public
domain".

License declarations on CTAN package pages are hints about the overall
status of the files in the package. They cannot be taken as
definitive. It is common for a package to have some files under license
x and other files under license y, e.g., a README or other doc under one
license and code under another.

The restrictive statement in tex/mf.web was important during the early
years of development (e.g., when there were no other engines), to avoid
proliferation of many slightly different files named tex.web for
different systems, and when tex.web itself was being actively changed by
DEK. That is not an issue these days. Knuth is well aware of the
existence of pdftex.web, xetex.web, etc., all of which started life as
tex.web, and he hasn't complained, so the purported restrictions
are obviously not an issue for him.

Although it would be ideal to change the tex/mf.web copyright statement,
he has stated his wishes ("public domain") so many times, in so many
ways, I think he would be quite unhappy to be asked to spend yet more
time on it. So I cannot contemplate asking him for changes here. -k