--- /dev/null
+.. _symmetry_page:
+
+********
+Symmetry
+********
+
+This geometrical operation allows to perform a symmetrical copy of your mesh or some of its elements.
+
+*To create a symmetrical copy:*
+
+.. |img| image:: ../images/symmetry.png
+
+#. From the **Modification** menu choose **Transformation** -> **Symmetry** item or click *"Symmetry"* button |img| in the toolbar.
+
+ The following dialogs will appear, where you can choose a way to mirror:
+
+ * through a point:
+
+ .. image:: ../images/symmetry1.png
+ :align: center
+
+ * through an axis:
+
+ .. image:: ../images/symmetry2.png
+ :align: center
+
+ * through a plane (defined by a point and a normal to the plane):
+
+ .. image:: ../images/symmetry3.png
+ :align: center
+
+
+#. In the dialog:
+
+ * specify the elements for the symmetry operation:
+
+ * **Select the whole mesh, submesh or group** activating this checkbox; or
+ * choose mesh elements with the mouse in the 3D Viewer. It is possible to select a whole area with a mouse frame; or
+ * input the element IDs directly in **ID Elements** field. The selected elements will be highlighted in the viewer; or
+ * apply Filters. **Set Filter** button allows to apply a :ref:`filtering_elements` to the selection of elements.
+
+ * depending on the nature of the mirror object:
+
+ * if the mesh is mirrored through a point, specify the coordinates of the point, either directly or by picking a mesh node;
+ * if the mesh is mirrored through an axis:
+
+ * specify the coordinates of the start **Point** of the axis, either directly or by picking a mesh node;
+ * specify the components of axis **Vector**, either directly or by picking a mesh node, in which case **Vector** is defined as a shift between the **Point** and the node;
+
+ * if the mesh is mirrored through a plane:
+
+ * specify the coordinates of the **Point** lying on the plane, either directly or by picking a mesh node;
+ * specify the components of plane **Normal**, either directly or by picking a mesh node, in which case **Normal** is defined as a shift between the **Point** and the node.
+
+ * specify the conditions of symmetry operation:
+
+ * activate **Move elements** radio button to change the location of the selected elements within the current mesh;
+ * activate **Copy elements** radio button to duplicate the selected elements at the new location within the current mesh;
+ * activate **Create as new mesh** radio button to create a new element in a new mesh; the new mesh appears in the Object Browser with the default name *MeshName_mirrored* (it is possible to change this name in the adjacent box);
+ * activate **Copy groups** check-box to put new mesh entities into new groups if source entities belong to some groups. New groups are named by pattern "<old group name>_mirrored".
+
+ * activate **Preview** check-box to show the result of transformation in the viewer;
+ * click **Apply** or **Apply and Close** button to confirm the operation.
+
+
+**See Also** a sample TUI Script of a
+:ref:`tui_symmetry` operation.
+
+
