Dual licensing

Dual licensing is when you release your software under two or more licenses at the same time.

Any code you want to integrate in your software, and for which you do not hold the copyright, must be compatible with both licenses.

You also need the permission of all copyright holders of the code if you want to pass from a single-licensing to a dual-licensing scheme.

Example copyright notice, for GNU GPL + EPL:

You may copy, modify, and redistribute this file under the terms
of the GNU General Public License version 2 (or, at your option,
any later version), or the Eclipse Public License version 1.0.

[standard GPL notice]

[standard EPL notice]