Revision control
++ <svg viewBox="0 0 200 200" xmlns="http://www.w3.org/2000/svg">
++ <pattern id="pattern" patternUnits="objectBoundingBox" patternContentUnits="userSpaceOnUse"
++ x="0.1" y="0.1" width="0.2" height="0.2">
++ <rect x="0" y="0" width="20" height="20" fill="red"/>
++ <rect x="20" y="0" width="20" height="20" fill="green"/>
++ <rect x="0" y="20" width="20" height="20" fill="blue"/>
++ <rect x="20" y="20" width="20" height="20" fill="yellow"/>
++ </pattern>
++ <rect width="200" height="200" fill="url(#pattern)"/>
++ </svg>
++