This category is for images marked with {{GFDL}}:

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "Text of the GNU Free Documentation License".

Generally, every wiki page uses the GNU FDL. This tag and category is necessary for images using the GNU FDL. This is to distinguish it from, for example, NetHack screenshots and fair use images, which themselves are not under the GNU FDL.