diff --git a/doc/salome/gui/SMESH/input/viewing_meshes_overview.doc b/doc/salome/gui/SMESH/input/viewing_meshes_overview.doc
index 8c7145787..9039b9365 100644
--- a/doc/salome/gui/SMESH/input/viewing_meshes_overview.doc
+++ b/doc/salome/gui/SMESH/input/viewing_meshes_overview.doc
@@ -37,7 +37,9 @@ Faces, Edges or both.</li>
 <li><b>2D Quadratic</b> - allows to select between the representation
 of quadratic edges as broken <b>lines</b> or as <b>arcs</b></li>
 <li><b>Orientation of faces</b> - shows vectors of orientation of
-faces of the selected mesh</li> 
+faces of the selected mesh. Vector is shown for each 2D mesh element 
+and for each free face of 3D mesh element. Vector direction is calculated by 
+the first three nodes of face as a cross product of vectors n1-n2 and n1-n3.</li> 
 <li><b>Colors / Size</b> - allows to select color and size of
 meshes.</li>
 <li>\subpage transparency_page "Transparency" - allows to change the