+<br>
+\anchor mode_group_boundary_anchor
+<h2>Duplicate nodes on group boundaries</h2>
+
+This mode duplicates nodes located on boundaries between given groups of
+volumes. If required, flat elements are created on the duplicated
+nodes: a triangular facet shared by two volumes of two groups generates
+a flat prism, a quadrangular facet generates a flat hexahedron.
+<br>
+The created flat volumes are stored in groups. These groups are named
+according to the position of the group in the list of groups: group
+"j_n_p" is a group of flat elements that are built between the group \#n
+and the group \#p in the group list. All the flat elements are gathered
+into the group named "joints3D". The flat element of the multiple
+junctions between the simple junction are stored in a group named
+"jointsMultiples".
+
+<br>
+
+\image html duplicate04.png
+
+Parameters to be defined in this mode:
+<ul>
+<li><b>Groups of volumes</b> (<em>mandatory</em>): list of volume
+ groups. These groups should be disjoint, i.e. should not share volumes.</li>
+<li><b>Create joint elements</b> : if checked - the flat elements are created.</li>
+<li><b>On all boundaries</b> : if checked - then the volumes not
+ included into the <b>Groups of volumes</b> are considered as another given
+ group. And thus nodes on boundary between <b>Groups of volumes</b> and the
+ rest mesh are also duplicated.</li>
+</ul>
+