RailwayRouteOptimization/scripts/Select/doc/Select_desc_en.html

<div>
  <a name="cross" />
  <p>
    <i>Cross Selection</i>
  </p>
  <p>Some selection tools can be used in cross selection mode. In this mode,
  not only entities that are completely inside a given area are selected but
  also entities that are only partly inside the area. This selection is also
  known as "cross selection".</p>
  <a name="mode" />
  <p>
    <i>Selection Mode</i>
  </p>
  <p>Some selection tools allow you to choose a selection mode in the options
  toolbar. The selection modes that are available are: 
  <ul>
    <li>Replace selection: 
    <br />
    <img src="SelectionModeReplace.png" width="40" height="40" />
    <br />Replaces the current selection with the new selection made by the
    active selection tool (default).</li>
    <li>Add to selection: 
    <br />
    <img src="SelectionModeAdd.png" width="40" height="40" />
    <br />Adds the selection to the current selection.</li>
    <li>Remove from selection: 
    <br />
    <img src="SelectionModeRemove.png" width="40" height="40" />
    <br />Removes (subtracts) the selection from the current selection.</li>
    <li>Intersect: 
    <br />
    <img src="SelectionModeIntersect.png" width="40" height="40" />
    <br />Only entities that were already selected and that match the criteria
    of the selection tool are selected.</li>
  </ul></p>
</div>