What does "copyleft" mean in the AWS Lumberyard terms of service?
By Marc Jones

Amazon makes a “free” game engine that is a source available and royalty free. No one is arguing that it is Free Software or “open source” but an interesting term caught my eye and made me wonder, do I know what “copyleft” means? Do I know what it means in the context of this license agreement?

The Lumberyard License says “you may not …. take any action that would require us or you to license, distribute, or otherwise make available to anyone the Lumberyard Materials under different terms (e.g., combining Lumberyard Materials with software subject to “copyleft” open source licenses)”.

This presentation will explore copyleft itself by looking at some prominent definitions of “copyleft” and then review some real licenses to see what are the boundaries of copyleft, what is the minimum requirements to be a copyleft? Does copyleft have to be Free Software? Does it have to be extent freedoms to derivative works? Does it have to extend the same freedoms to derivative works?

• OSI - defines copyleft as ""Copyleft" refers to licenses that allow derivative works but require them to use the same license as the original work."

• FSF - defines copyleft as "Copyleft is a general method for making a program (or other work) free (in the sense of freedom, not “zero price”), and requiring all modified and extended versions of the program to be free as well."

• Copyleft.org defines it using the wikipedia definition as "Copyleft is a strategy of utilizing copyright law to pursue the policy goal of fostering and encouraging the equal and inalienable right to copy, share, modify and improve creative works of authorship. Copyleft (as a general term) describes any method that utilizes the copyright system to achieve the aforementioned goal."

These are three very different definitions. I think they are great descriptions of copyleft, but which one is right. I am honestly not sure, if only one is right. This talk will look a several prominent and not so prominent licenses that are regarded as copyleft to explore the scope of copyleft.

Traditionally copyleft licenses are often divided into strong and weak copyleft. Do all copyleft licenses fit into those categories? Can you a copyleft license and not be Free Software or Open Source software.

We will first look at a few of the prominent copyleft licenses such as GPL, MPL, and LGPL to see how traditional copyleft licenses work. Then we will look at some other licenses such as:

• Business Source License (https://mariadb.com/bsl11/)- a license that permits modification and redistribution under the terms of the license BSL, but not consider FOSS by anyone
• Amazon Software License (https://aws.amazon.com/asl/)- Software needs to be redistributed under the same terms, but derivative works can be distributed under different terms so long as they include a specific use restriction.
• Reciprocal Public License (https://opensource.org/licenses/RPL-1.5) - a OSI approved, but classified as non-free by FSF license that forces modifications to be distributed to the public under the terms of the license under a variety of conditions.
• Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/legalcode) - Are creative commons licenses copyleft licenses? CC BY-SA requires redistribution of derivative works under the same license or a "compatible license"
• Creative Commons Attribution 4.0 International Public License (https://creativecommons.org/licenses/by/4.0/legalcode) - allows redistribution of derivative works under any license that does not prohibit receipts from exercising the rights granted by the license under the Licensed Material. Prohibits imposing effective Technological measures that might restrict the ability of a receipt to exercise license rights to the original material.