-<li><b>Group of elements to duplicate</b> (<em>mandatory</em>): these elements will be duplicated.</li>
-<li><b>Group of nodes at not to duplicate</b> (<em>optional</em>): group of nodes at crack bottom
- which will not be duplicated.</li>
-<li><b>Group of elements to replace nodes with new ones</b> (<em>mandatory</em>): the duplicated nodes
- will be associated with these elements.</li>
-<li><b>Construct group with newly created elements</b> option (<em>checked by default</em>):
- if checked - the group of just created elements will be built.</li>
-<li><b>Construct group with newly created nodes</b> option (<em>checked by default</em>):
- if checked - the group of just created nodes will be built.</li>
+<li><b>Group of elements to duplicate</b> (<em>mandatory</em>): these
+ elements will be duplicated.</li>
+<li><b>Group of nodes not to duplicate</b> (<em>optional</em>):
+ group of nodes at crack bottom which will not be duplicated.</li>
+<li><b>Group of elements to replace nodes with new ones</b>
+ (<em>mandatory</em>): the new nodes will replace the nodes to
+ duplicate within these elements. \b Generate button automatically
+ creates these groups.</li>
+<li><b>Construct group with newly created elements</b> option
+ (<em>checked by default</em>): if checked - the group of newly created
+ elements will be built.</li>
+<li><b>Construct group with newly created nodes</b> option
+ (<em>checked by default</em>): if checked - the group of newly
+ created nodes will be built.</li>
+</ul>
+
+A schema below explains the crack emulation using the node duplication
+with border elements.
+\image html crack_emulation_double_nodes_with_elems.png "Crack emulation"
+This schema shows a virtual crack in a 2D mesh created using this duplication
+mode. In this schema:
+- Black segments are <b>duplicated elements</b> (edges in 2D case).
+- Black balls (except for the lowest one) are duplicated nodes of <b>duplicated elements</b>.
+- The lowest black ball is the <b>non-duplicated node</b>.
+- Red balls are <b>newly created nodes</b>.
+- Red segments are <b>created elements</b> (edges).
+- <b>Elements to replace nodes with new ones</b> are marked with green.
+
+Note that in the reality <b>nodes to duplicate</b> coincide with <b>new nodes</b>.
+<br>
+In a 3D case, where <b>elements to duplicate</b> are faces, the edges
+located at the "crack" (if any) are cloned automatically.
+
+<br>
+\anchor mode_elem_only_anchor
+<h2>Duplicate elements only</h2>
+
+This mode duplicates the given elements, i.e. creates new elements with the same nodes as the given elements.
+<br>
+
+\image html duplicate03.png
+
+Parameters to be defined in this mode:
+<ul>
+ <li><b>Group of elements to duplicate</b> (<em>mandatory</em>): these
+ elements will be duplicated.</li>
+ <li><b>Construct group with newly created elements</b> option
+ (<em>checked by default</em>): if checked - the group of newly created
+ elements will be built. The name of the created group starts from
+ "DoubleElements".</li>