SNNS is distributed by the University of Stuttgart as `Free Software' in a licensing agreement similar in some aspects to the GNU General Public License. There are a number of important differences, however, regarding modifications and distribution of SNNS to third parties. Note also that SNNS is not part of the GNU software nor is any of its authors connected with the Free Software Foundation. We only share some common beliefs about software distribution. Note further that SNNS is NOT PUBLIC DOMAIN.
The SNNS License is designed to make sure that you have the freedom to give away verbatim copies of SNNS, that you receive source code or can get it if you want it and that you can change the software for your personal use; and that you know you can do these things.
We protect your and our rights with two steps: (1) copyright the software, and (2) offer you this license which gives you legal permission to copy and distribute the unmodified software or modify it for your own purpose.
In contrast to the GNU license we do not allow modified copies of our software to be distributed. You may, however, distribute your modifications as separate files (e.,g. patch files) along with our unmodified SNNS software. We encourage users to send changes and improvements which would benefit many other users to us so that all users may receive these improvements in a later version. The restriction not to distribute modified copies is also useful to prevent bug reports from someone else's modifications.
Also, for our protection, we want to make certain that everyone understands that there is NO WARRANTY OF ANY KIND for the SNNS software.