Hi,<br><br>In the last section of <a href="https://bitbucket.org/galaxy/galaxy-central/wiki/ToolsMultipleOutput">https://bitbucket.org/galaxy/galaxy-central/wiki/ToolsMultipleOutput</a>, &quot;Number of output datasets cannot be determined until tool run&quot;, it should be updated that the new additional datasets file format actually has a sixth part at the end where you can set the database attribute of the output dataset:<br>
<br>&quot;%s_%s_%s_%s_%s_%s&quot; % ( &#39;primary&#39;, <a href="http://output1.id">output1.id</a>, name, &#39;visible&#39;,  file_type, database )<br><br>I accidentally discovered this even though I didn&#39;t want to set the database attribute because I have some custom datatypes defined and my datatype extension names have underscores in them :) which causes Galaxy to think that the part of my extension names string after the underscore is actually the database name i want to set.<br>
<br>I would recommend not to put underscores in your custom datatype extension names :)  <br><br>-Leandro<br>