<svg xmlns="http://www.w3.org/2000/svg" xmlns:xl="http://www.w3.org/1999/xlink">
<defs>
<filter id="foo" filterUnits="userSpaceOnUse">
    <feGaussianBlur in="SourceAlpha" stdDeviation="3"/>
</filter>
</defs>
<g>
    <g style="filter:url(#foo)"/>
</g>
</svg>