<em>To union several triangles:</em>
<ol>
-<li>Display a mesh or a submesh in the 3D viewer.</li>
+<li>Display a mesh or a sub-mesh in the 3D viewer.</li>
<li>In the \b Modification menu select the <b>Union of triangles</b>
item or click <em>"Union of triangles"</em> button in the toolbar.
to sort the list of IDs. The <b>Set filter</b> button allows to apply a
definite filter to selection of triangles.</li>
<li><b>Apply to all</b> radio button allows to modify connectivity and
-type of all triangles of the currently displayed mesh or submesh.</li>
-<li>\b Criterion menu allows to apply the operation only to those
-object which meet the chosen criterion (from the list of Quality
-Controls, i.e. Skew, Warping, Minimum Angle, etc.)</li>
-<li><b>Select from</b> set of fields allows to choose a submesh or an
+type of all triangles of the currently displayed mesh or sub-mesh.</li>
+<li><b>Preview</b> provides a preview in the viewer.</li>
+<li>\b Criterion menu allows to choose a quality criterion,
+ which will be optimized to select triangles to unite.</li>
+<li><b>Select from</b> set of fields allows to choose a sub-mesh or an
existing group whose triangle elements will be automatically added to
the list.</li>
</ul>
