/*!

\page grouping_elements_page Grouping elements

In Mesh module it is possible to create groups of mesh elements:
nodes, edges, faces or volumes. One group contains elements of only
one type. The following ways of creation are possible:

<ul>
<li> by selecting the elements using filters and/or
  directly on the presentation in the VTK viewer, and/or by using
  elements of other mesh objects - <b>Standalone group</b> tab of 
  \ref standalone_group "Create group" dialog.</li>
<li> by creating a group of elements generated on the chosen
  geometrical object - <b>Group on geometry</b> tab of \ref
  creating_groups_page "Create group" dialog and \ref
  create_groups_from_geometry_page "Create Groups from Geometry"
  dialog.</li>
<li> by creating a group of elements satisfying to certain critaria -
  <b>Group on filter</b> tab of \ref creating_groups_page 
  "Create group" dialog.</li>
<li> by creating groups of nodes and elements from the chosen submesh
  (type of elements depends on dimension of submesh geometry) -
  using <b>Mesh -> Construct Group</b> menu item (available in contextual
  menu as well).</li>
<li> by creating groups of entities from existing groups of superior
  dimensions - using \subpage group_of_underlying_elements_page
  "Create Group of Underlying Elements" dialog.</li>
</ul>


The created groups can be later:

<ul>
<li>\subpage editing_groups_page "Edited"</li>
<li>\subpage using_operations_on_groups_page "Subjected to Boolean operations"</li>
<li>\subpage deleting_groups_page "Deleted"</li>
</ul>

An important tool, providing filters for creation of \b Standalone
groups is \ref selection_filter_library_page.


*/