<!DOCTYPE html>
<base href="http://www.example.com/">
<svg>
  <marker id="marker" refY="0.5">
    <rect width="1" height="1" fill="green"/>
  </marker>
  <polyline points="0,50 100,50 200,50" stroke="red" stroke-width="100"
            marker-start="url(#marker)" marker-mid="url(#marker)" marker-end="url(#marker)"/>
</svg>