I am not sure if GNU's legal conditions are precisely what we want--especially the nickname ``copyleft''. But GNU has researched the legal side of this issue so thoroughly that I am choosing to use the ``GNU general public license'' which is attached.
I hope you will respect the legal rights of my paper book publisher and not make paper copies of the book. I hold the electronic rights. Please see the GNU General Public License which offers you various electronic rights. I would like you to be able to do what you like with my software, but my employer would like to benefit from any possible commercial applications you might come up with. If you want to make a product, I will help you communicate with my University's licensing office. They are nice people and I believe they accept reasonable offers. If your employer is a sponsor of the Stanford Exploration Project, you already have an option for a non-exclusive royalty-free license. If your company is a sponsor of the Stanford Exploration Project, then you already have an option for a free license so then you can forget about the more restrictive GNU public license (as far as my software is concerned).