Grouping by shift problem

<shifts>
   <shift1 start='00:00:00' end='08:00:00'/>
   <shift2 start='08:00:00' end='16:00:00'/>
   <shift3 start='16:00:00' end='00:00:00'/>
</shifts>

<departs>
   <door>
   <time>2005-06-12T15:02:06</time>
   <name>Joe Somebody</name>
   <dock>032</dock>
   </door>
   <door>
   <time>2005-06-13T17:03:56</time>
   <name>Joe Somebodyelse</name>
   <dock>055</dock>
   </door>
   ...
</departs>

like thus,
<alldeparts>
<shift2>
   <depart>
   <name>Joe Somebody</name>
   <time>2005-06-13T17:03:56</time>
   <dock>055</dock>
   </depart>
...
</shift2>
<shift3>
   <depart>
   <time>2005-06-13T17:03:56</time>
   <name>Joe Somebodyelse</name>
   <dock>055</dock>
   </depart>
...
</shift3>
...
</alldeparts>
etc.