MediaWiki:Licenses

 <select>
   <optgroup label="Most used licenses">
     <option val="1">Creative Commons Attribution Share-Alike 3.0 License</option>
     <option val="2">GNU Free Documentation License (Version 1.2 or later)</option>
   </optgroup>
   <optgroup label="All licenses alphabetically">
     <option val="1">Creative Commons Attribution 3.0 License</option>
     <option val="4">Creative Commons Attribution Share-Alike 3.0 License</option>
     <option val="2">GNU Free Documentation License (Version 1.2 or later)</option>
     <option val="12">The Awesome Something License</option>
   </optgroup>
 </select>