<smil>
  <head>
    <layout>
      <region id="c2" top="0" left="0" height="98" width="250"/>
      <region id="c3" top="98" left="0" height="75" width="250"/>
    </layout>
  </head>
  <body>
    <par>
       <img id="i1" src="http://smil.nist.gov/interop1/getout.jpg"
            begin="2s" region="c2"
       />
       <img src="http://smil.nist.gov/interop1/choose.jpg"
            region="c3"
            begin="id(i1)(3s)"/>
    </par>
  </body>
</smil>