<svg width="300" height="200"> <!-- note: no namespace, but sent as image/svg+xml -->
 <desc>There should be no red on this page.</desc>
 <rect x="10" y="10" width="280" height="180" fill="red"/>

 <!-- This document is either not SVG, or is SVG but is in error.
      Section 5.1.1 of SVG 1.1 says:
      # In all cases, for compliance with the "Namespaces in XML"
      # Recommendation [XML-NS], an SVG namespace declaration must be
      # provided so that all SVG elements are identified as belonging
      # to the SVG namespace.
  -->

</svg>