🚀 go-pugleaf

I was reading an old Seybold Report last night and encountered the following
statement:

"Knuth's source code for Tex has been published by Addison-Wesley (Reading,
MA) and can be licensed for commercial purposes at nominal cost from the
American Mathematical Society (Long Island, NY)."

(The Seybold Report on Desktop Publishing, April 4, 1988, p. 12)

Yet the copyright notice on TeX:The Program says that Knuth has placed the
program TeX into the public domain, and that the reader is free to use the
algorithms in his own code.  Further reading indicates that only programs
which conform exactly (other than system dependencies) to the published
algorithms may be called TeX.  There is no mention of licensing requirements
or fees for any purpose, including commercial use.

What's the real story? Are the TeX algorithms in the public domain only
if the use is non-commercial?  Why doesn't the copyright notice in TeX:The 
Program say that?  What would really hold in court?

Dave Kumpf
hplabs!hp-lsd!davek
davek%hp-lsd@hplabs.hp.com