To list your file in JED under a GPL license, you must include proper notices for the license chosen. Its easy as A, B, C!

[edit] (A) XML file

A <license> tag in your extension's XML file and state it is licensed under the GPL, as in this tags for a module:

<?xml version="1.0" encoding="utf-8"?>
<install type="module" version="1.5.0">
        <name>Extension name goes here</name>
        <creationDate>20 April 2010</creationDate>
        <author>Author name goes here</author>
        <copyright>Copyright holder name goes here</copyright>
        <license>GNU/GPLv3 http://www.gnu.org/licenses/gpl-3.0.html</license>
        <authorEmail>you@youremail.com</authorEmail>
        <authorUrl>http://www.yoursite.com</authorUrl>
        <version>1.0</version>
        <description>DESCRIPTION GOES HERE</description>

For GPL you can use other versions of the license, but GNU/GPLv3 is preferable:

• GNU/GPL http://www.gnu.org/copyleft/gpl.html
• GNU/GPL v2 or later http://www.gnu.org/licenses/gpl-2.0.html
• GNU/GPLv3 http://www.gnu.org/licenses/gpl-3.0.html

[edit] (B) PHP files

The file headers of an extension should contain a copyright notice and a notice that the file and extension is distributed under the terms of the GPL, as in this comment block:

<?php
/**
 * @package Module XYZ for Joomla! 1.5
 * @version $Id: mod_XYZ.php 599 2010-03-20 23:26:33Z you $
 * @author YOUR NAME HERE
 * @copyright (C) 2010- YOUR NAME HERE
 * @license GNU/GPLv3 http://www.gnu.org/licenses/gpl-3.0.html
**/

Note: Additional informations about the extension, author, copyright and version date are considered good practices

[edit] (C) TXT file

Provide a copy of the GPL license within your package

• GNU GPL v2 text

note: this file doesn't need to be installed with the extension, just included with the package as a text file

[edit] Special cases

[edit] Tools

Tools for creating and maintaining Joomla! websites or for developing Joomla! extensions, but not meant to be installed or change core files in Joomla!, are listed under category "Tools". They can be licensed under other licenses

• You must include a TXT file for license info

[edit] Independent Libraries

Libraries (as in Js scripts) single packed can be licensed under a GPL compatible license listed by the Free Software Foundation, as in LGPL:

• LGPLv3 - http://www.gnu.org/licenses/lgpl-3.0.html

You must include a TXT file for license info

[edit] Files packed with extensions

[edit] Libraries packed with extensions

Libraries which can stand alone (as in Js scripts) can be licensed under GPL compatible licenses as in:

• LGPLv3 - http://www.gnu.org/licenses/lgpl-3.0.html

You must include a TXT file for license info and a statement in the extension XML file license tag

[edit] Non code files

Non code files which can stand alone (as in Images, compiled flash files), packed with extensions, can be licensed under other licenses.

• You must include a TXT file for license info and a statement in the extension XML file license tag

[edit] Additional Reading

Before submitting an extension to JED, please read:

• FAQ: Extensions_and_GPL
• JED editors Checklist: JED_Entries_License_Checklist