<svg xmlns="http://www.w3.org/2000/svg"
     xmlns:xlink="http://www.w3.org/1999/xlink">

<defs>
 <pattern id="dot" width="1" height="1">
  <circle cx="20" cy="50" r="10" fill="black" />
 </pattern>
</defs>

<text text-anchor="middle" x="200" y="100">There should be a black dot in the middle of the ellipse</text>
<ellipse cx="200" cy="200" rx="20" ry="50" fill="url(#dot)" stroke="gray" />
</svg>