<?xml version="1.0"?>

<svg xmlns="http://www.w3.org/2000/svg" 
  xmlns:xlink="http://www.w3.org/1999/xlink"
  viewBox="0 0 100 100">
  <defs>
    <rect id="r" width="50" height="50" 
      stroke="black" stroke-width="3"/>
  </defs>
  <rect x="0" y="0" width="100" height="100" stroke="blue" stroke-width="1" fill="none"/>
  <use xlink:href="#r" x="10" y="10" fill="yellow"/>
  <use xlink:href="#r" x="40" y="40" fill="lime"/>
</svg>

