-<li>\b Remove button deletes the selected group from the list.</li>
-<li>\b Add button adds to the list a group of elements selected in the
-viewer with pressed "Shift" key.</li>
-<li><b>Select all</b> checkbox selects all groups.</li>
+ <li>\b Detect button generates the list of coincident elements found
+ in the selected object.</li>
+ <li><b>Coincident elements</b> is a list of groups of elements for
+ merging. After the operation all elements of each group will
+ be united into one element. The first element of a group is kept and
+ the others are removed.
+ <li>\b Remove button deletes the selected group from the list.</li>
+ <li>\b Add button adds to the list a group of elements selected in the
+ viewer with pressed "Shift" key.</li>
+ <li><b>Select all</b> check-box selects all groups.</li>
+ <li><b>Show double elements IDs</b> check-box shows/hides identifiers of
+ elements of the selected groups in the 3D viewer.</li>
+ <li><b>Edit selected group of coincident elements</b> list allows
+ editing the selected group:
+ <br><br>
+ \image html add.png
+ <center>adds to the group the elements selected in the viewer.</center>
+ <br>
+ \image html remove.png
+ <center>removes the selected elements from the group.</center>
+ <br>
+ \image html sort.png
+ <center>moves the selected element to the first position in the
+ group in order to keep it in the mesh.</center>
+ <br>
+ </li>