<?xml version=“1.0” standalone=“yes”?> <svg width=“4in” height=“3in”

xmlns = 'http://www.w3.org/Graphics/SVG/svg-19990412.dtd'>
 <desc>This example uses the switch element to provide a 
 fallback graphical representation of an equation, if 
 MathML is not supported.
 </desc>
 <!-- The <switch> element will process the first child element
      whose testing attributes evaluate to true.-->
 <switch>

   <!-- Process the MathML if the system-required attribute
        evaluates to true (i.e., the user agent supports MathML
        embedded within SVG). -->
   <foreignobject 
      system-required="http://www.w3.org/TR/REC-MathML-19980407" 
      width="100" height="50">
     <!-- MathML content goes here -->
   </foreignobject>

   <!-- Else, process the following alternate SVG.
        Note that there are no testing attributes on the <g> element.
        If no testing attributes are provided, it is as if there
        were testing attributes and they evaluated to true.-->
   <g>
     <!-- Draw a red rectangle with a text string on top. -->
     <rect style="fill: red"/>
     <text>Formula goes here</text>
   </g>

 </switch>

</svg>