In creating e-TeX, we have followed his example: we release e-TeX to the world under exactly the same conditions as Don released TeX. The name e-TeX is a trademark of the NTS group, as are its typeset and HTML logos. No package may describe itself as "e-TeX" unless (a) it is generated using the official source files from the e-TeX reference site, together with such system-dependent changes as are necessary and permitted in order for it to run on a specific system, and (b) it has been validated for conformity using the e-TRIP test.
No changes shall be made by anyone other than a member of the NTS group to any of the files which form a part of the e-TeX distribution. If, for whatever reason, someone other than a member of the NTS group wishes to change such a file, then he or she shall (a) add a comment indicating the reason for, and nature of the change, together with the date and the name of the person making the change, and (b) shall save the changed file under a different name, so that there shall exist no risk of confusion between the changed file and the authoritative official version.
Although it is preferred that e-TeX be distributed in source form, it is recognised that there are systems for which binary distributions are the norm. It is therefore requested that any binary distribution of e-TeX be accompanied by a clear statement that the definitive sources for e-TeX are available free-of-charge at the e-TeX reference site.
With the exception of anything specifically referred to above, all components of the system known as "e-TeX" are released under exactly the same terms and conditions as the system known as "TeX".
Enjoy!