Mapping Logic: XML Node output

Hi Guys,

Could you please help me on a mapping logic that I need.

I have the following source xml format. The source and target message are the same.

<MessageType>
<Node>
  <ItemCount>1000</ItemCount>
  <BASE>ABC</BASE>
</Node>
<Node>
  <ItemCount>1001</ItemCount>
  <AMOUNT>ABC</AMOUNT>
</Node>
<Node>
  <ItemCount>1002</ItemCount>
  <RATE>ABC<RATE>
</Node>
</MessageType>

If RATE Exists then, it will output all Nodes.
Else, if it does not exist, it will only output first occurrence of the node.

Thanks and Regards,

Neil