chromium/third_party/blink/web_tests/svg/custom/circular-marker-reference-1.svg

<?xml version="1.0" encoding="ISO-8859-1"?>

<svg xmlns="http://www.w3.org/2000/svg" viewBox="-10 -10 20 20"
  stroke="#000" stroke-linecap="round"
  >

  <defs>
    <marker id="mark" viewBox="0 0 8 8" refX="4" refY="4" markerWidth="3" markerHeight="3">
  <path marker-start="url(#mark)" marker-mid="url(#mark)" marker-end="url(#mark)" d="M-5,-2h5h5"/>
    </marker>
  </defs>

  <path d="M-5,+2h5h5"
    marker-start="url(#mark)" marker-mid="url(#mark)" marker-end="url(#mark)"/>

</svg>