<span xml:space="default">
  <!-- Always preserve CDATA whitespace -->       
</span>
<p xml:space="default">
  <!-- The u element has multiple text, whitespace, and element children.  The element children change xml:space. -->
  <u xml:space="preserve"> Hello<u xml:space="default"></u>  <u xml:space="default" />  <b>World </b>  </u>
</p>