SVG / Inkscape /遮罩

Question

以下SVG显示集合的对称差异：

<svg xmlns="http://www.w3.org/2000/svg" xmlns:ev="http://www.w3.org/2001/xml-events" xmlns:xlink="http://www.w3.org/1999/xlink" baseProfile="full" height="3.2cm" version="1.1" viewBox="0 0 5 3.2" width="5.0cm">
<defs/>
<pattern height="0.14142135623730953" id="4" patternUnits="userSpaceOnUse" width="0.14142135623730953">
    <path d="M -0.07071067811865477,0.07071067811865477 l 0.14142135623730953,-0.14142135623730953 M -0.07071067811865477,0.21213203435596428 l 0.28284271247461906,-0.28284271247461906 M 0.07071067811865477,0.21213203435596428 l 0.14142135623730953,-0.14142135623730953" style="stroke:black; stroke-width:0.02"/>
</pattern>
<mask id="m1">
    <circle cx="2" cy="1.6" fill="white" r="1.5"/>
    <circle cx="3" cy="1.6" fill="black" r="1.5"/>
</mask>
<mask id="m2">
    <circle cx="3" cy="1.6" fill="white" r="1.5"/>
    <circle cx="2" cy="1.6" fill="black" r="1.5"/>
</mask>
<circle cx="2" cy="1.6" fill="url(#4)" mask="url(#m1)" r="1.5" stroke="black" stroke-width="0.04"/>
<circle cx="3" cy="1.6" fill="url(#4)" mask="url(#m2)" r="1.5" stroke="black" stroke-width="0.04"/>
<circle cx="2" cy="1.6" fill="none" r="1.5" stroke="black" stroke-width="0.04"/>
<circle cx="3" cy="1.6" fill="none" r="1.5" stroke="black" stroke-width="0.04"/>
</svg>

它在浏览器中有效： -s switch 但是使用Inkscape可以获取以下版本的Latex文档：

  

我的SVG是否不正确（但是浏览器可以容错），或者Inkscape有限制吗？ （忘掉文字）