cpython/Lib/test/xmltestdata/c14n-20/inNsXml.xml

<foo xmlns="http://z0" xml:id="23">
  <bar xsi:type="xsd:string" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">data</bar>
</foo>