% This macro file belongs to the public domain % under the conditions specified by the author of TeX: % % ``Macro files like PLAIN.TEX should not be changed in any way, % except with respect to preloaded fonts, % unless the changes are authorized by the authors of the macros.'' % % Donald E. Knuth % % For details see MEXINFO.ENG or MEXINFO.POL.
It's clearly nonfree and different that what Knuth states in plain.tex: % Unlimited copying and redistribution of this file are permitted as long % as this file is not modified. Modifications are permitted, but only if % the resulting file is not named plain.tex. I cant see any contradiction plain.tex cannot be changed but if you rename as plain-pepito.tex is everything ok
