-<li>the type of elements which will be extruded (1D or 2D),</li>
-<li>specify the IDs of the elements which will be extruded by
-selecting them in the 3D viewer or select the whole mesh or
-submesh,</li>
-<li>specify the vector along which the elements will be extruded,</li>
-<li>number of steps.</li>
+ <li>Select the type of elements which will be extruded (0D, 1D or 2D).</li>
+ <li>Specify the IDs of the elements which will be extruded by one
+ following means:
+ <ul>
+ <li><b>Select the whole mesh, submesh or group</b> activating this
+ checkbox.</li>
+ <li>Choose mesh elements with the mouse in the 3D Viewer. It is
+ possible to select a whole area with a mouse frame.</li>
+ <li>Input the element IDs directly in <b>ID Elements</b>
+ field. The selected elements will be highlighted in the viewer.</li>
+ <li>Apply Filters. <b>Set filter</b> button allows to apply a
+ filter to the selection of elements. See more about filters in
+ the \ref filtering_elements "Selection filters" page.</li>
+ </ul>
+ </li>
+ <li>If the <b>Extrude to Distance</b> radio button is selected</li>
+ <ul>
+ <li>specify the distance at which the elements will be extruded.</li>
+ </ul>
+ <li>If the <b>Extrude Along Vector</b> radio button is selected</li>
+ <ul>
+ <li>specify the coordinates of the vector along which the elements
+ will be extruded, or select the face (the normal to the face will
+ define the vector),</li>
+ <li>specify the distance of extrusion along the vector.</li>
+ </ul>
+ <li>Specify the number of steps.</li>
+ <li>If you activate <b>Generate Groups</b> check-box, the created
+ elements contained in groups will be included into new groups named
+ by pattern "<old group name>_extruded" and "<old group name>_top".</li>