THIS IS THE OPEN SOURCE VERSION OF PyQt, RELEASED UNDER THE GPL LICENSE. PLEASE READ THIS FILE TO FIND OUT WHAT THAT MEANS TO YOU. INTRODUCTION ============ PyQt is licensed under two licenses: the GNU General Public License (GPL) and a commercial license. You are currently using the Open Source (GPL) version of PyQt. This file explains the principle of dual licensing, and which obligations using the GPL version of PyQt implies. ABOUT DUAL LICENSING ==================== Dual Licensing is based on the principle of Quid Pro Quo - something for something. If you, your company or your organization derive commercial benefit from Riverbank's products and do not wish to release your complete source code, you are required to purchase the appropriate number of commercial licenses. Alternatively, if you are willing to follow the terms of the GPL (General Public License), Riverbank software is available to you under Open Source licenses which allows you to develop, modify and distribute your software freely. If you wish to use an open source version of Riverbank's products, you must contribute all your source code to the open source community, according to the terms of the applicable open source license. By offering both open source and commercial licenses, Riverbank ensures the availability of resources for ongoing development and improvement of PyQt. By purchasing commercial licenses, you are no longer obligated to publish your source code. COMMERCIAL AND OPEN SOURCE LICENSES =================================== Riverbanks's Commercial licenses allow customers to develop, use and distribute their applications under standard commercial terms. Riverbanks's Open Source versions are available under the terms of the GPL - General Public License. The main obligation for software development under the GPL is that anyone using your PyQt-based software must have access to the complete source code, and must be able to modify and redistribute that software to anyone free of charge.