How is GPLv3 compatible with other GNU licenses?
The various GNU licenses enjoy broad compatibility between each other. The only time you may not be able to combine code under two of these licenses is when you want to use code that’s only under an older version of a license with code that’s under a newer version. Below is a detailed compatibility matrix for various combinations of the GNU licenses, to provide an easy-to-use reference for specific cases. It assumes that someone else has written some software under one of these licenses, and you want to somehow incorporate code from that into a project that you’re releasing (either your own original work, or a modified version of someone else’s GPLed software). Find the license for your own work in a column at the top of the table, and the license for the other code in a row on the left. The cell where they meet will tell you whether or not this combination is permitted. When we say “copy code,” we mean just that: you’re taking a section of code from one source, with or without modific
