What exactly mergedir mean?

[Leandro Melo]

Hi,
i'm a ant beginner.
I don't quite understand what is the merge dir. For instance, in the following code, what does the mergedir represent?

<hibernatedoclet
  destdir="${project.dir}/${hbm.dir}"
    excludedtags="@version,@author,@todo"
   force="${xdoclet.force}"
   mergedir="${ejb.dd.dir}"
    verbose="true">
  <fileset dir="${project.dir}/src">
               <include name="**/hibernate/*.java"/>
       </fileset>
  <hibernate version="2.0"/>
      </hibernatedoclet> 

Thanks,
ltcmelo