-Sub-mesh is a mesh on a geometrical sub-object created with algorithms
-and/or hypotheses other than the algorithms and hypotheses assigned to
-the parent mesh on the parent object.
-<br><br>
+Sub-mesh is a mesh on a geometrical sub-object (sub-shape) used to assign
+different meshing algorithms and/or hypotheses than the algorithms and
+hypotheses assigned to the parent mesh on the parent geometrical
+object, that allows getting a local mesh refinement.
+
+A sub-shape to create a sub-mesh on should be retrieved from the shape
+of the parent mesh one of the following ways: <ul>
+<li> In Geometry module, via <em>New Entity > Explode</em> menu.</li>
+<li> In Geometry module, by creation of a group (<em>New Entity >
+ Group > Create Group</em> menu).</li>
+<li> In Mesh module, by
+ \ref subshape_by_mesh_elem "selecting a mesh element" generated on a
+ sub-shape of interest. This way is accessible if the mesh is
+ already computed.</li>
+</ul>
+