edge-connector.xml

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    <style>
        <![CDATA[
            rect { fill: white; stroke: black; stroke-width: 0.1px; }
            line, polyline { stroke-width: 0.2px; stroke: black; fill: none; }
            text { font-size: 3px; dominant-baseline: central; text-anchor: middle; }
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    <polyline start="#a@t:-1" end="#b@t:1" corner-offset="1" marker-end="url(#arrow)"/>
    <polyline start="#a@t:-2" end="#b@t:100%" corner-offset="2" marker-end="url(#arrow)"/>
    <polyline start="#a@r" end="#b@l:20%" marker-end="url(#arrow)"/>
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