This is a zlib variant, less restrictive. It was found on the "newsletr" component of texlive 2010. It is Free and GPL-compatible.
% Copyright 1989--2004 by Hunter Goatley. % % Permission is granted to anyone to use this software for any purpose % on any computer system, and to redistribute it freely, subject to the % following restrictions: % % 1. This software is distributed in the hope that it will be useful, % but WITHOUT ANY WARRANTY; without even the implied warranty of % MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. % % 2. Altered versions must be plainly marked as such, and must not be % misrepresented as being the original software.