RailwayRouteOptimization/scripts/Snap/SnapDistance/doc/SnapDistance_proc_en.html

<div>
  <ol>
    <li>Enter the distance into the options toolbar.</li>
    <li>Move the cursor to the entity along which the distance should be
    measured.</li>
    <li>When the desired position / preview is shown, click the left mouse
    button to set the coordinate.</li>
  </ol>
  <br />
  <img src="SnapDistanceFigure.png" class="figure" />
</div>