RailwayRouteOptimization/scripts/Draw/Polyline/DrawPolyline/doc/DrawPolyline_proc_en.html

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  <ol>
    <li>Specify the start point of the first polyline segment. You can use the
    mouse or enter a coordinate in the console.</li>
    <li>Specify the endpoint of the first polyline segment.</li>
    <li>Specify the endpoints of additional polyline segments.</li>
  </ol>
  <p>If the polyline contains arc segments, you can tick the "Arc" check box
  and enter the arc radius in the options tool bar when setting the endpoint of
  an arc segment. The arc will connect smoothly (tangential) to the last
  segment.</p>
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