<!doctype html>
<html>
  <head>
    <title>semantics</title>
  </head>
  <body>

    <!-- This verifies that annotations are not visible. -->
    <math>
      <semantics>
        <mi>x</mi>
        <annotation encoding="TeX">x</annotation>
        <annotation encoding="StarMath 5.0">x</annotation>
        <annotation-xml encoding="MathML-Content"><ci>x</ci></annotation-xml>
      </semantics>
   </math>
   <br/>

    <!-- This is not valid MathML but has become a standard hack to include SVG in MathML because of Gecko's initial implementation. -->
  <math>
    <semantics>
      <annotation-xml encoding="SVG1.1">
        <svg width="20px" height="20px">
          <rect width="20px" height="20px" fill="red" stroke="none"/>
        </svg>
      </annotation-xml>
    </semantics>
  </math>

  </body>
</html>