SIFParser can't parse complex SIF_ExtendedElement

[Matthew-Ricks-USBE]

Not sure if complex is the right word, but the SIFParser can't parse all the examples in the SIF specification (I'm using version 2.4) here:

<SIF_ExtendedElements>
  <SIF_ExtendedElement Name="ApplicationSubmissionStatus">4</SIF_ExtendedElement>
  <SIF_ExtendedElement Name="DynamicXml">
    <Parent xmlns="http://myapplication.com">
      <Child n="1">one</Child>
      <Child n="2" />
      <Child n="3">three</Child>
    </Parent>
  </SIF_ExtendedElement>
  <SIF_ExtendedElement Name="Note">
    <xhtml:strong xmlns:xhtml="http://www.w3.org/1999/xhtml">Double</xhtml:strong>-check submission status.
      </SIF_ExtendedElement>
</SIF_ExtendedElements>

Of the three SIF_ExtendedElement nodes in the example, only the ApplicationSubmissionStatus one parses successfully—the other two throw exceptions.