/**
* @defgroup feaccess Finite element access/FEValues classes
*
+ * The classes in this module are used when one wants to assemble matrices or
+ * vectors. They link finite elements, quadrature objects, and mappins: the
+ * finite element classes describes a finite element space on a unit cell
+ * (i.e. the unit line segment, square, or cube @f$[0,1]^d@f$), the quadrature
+ * classes describe where quadrature points are located and what weight they
+ * have, and the mapping classes describe how to map a point from the unit
+ * cell to a real cell and back. Since integration happens at quadrature
+ * points on the real cell, and needs to know their location as well as the
+ * values and gradients of finite element shape functions at these points. The
+ * FEValues class coordinates getting this information. For integrations on
+ * faces (for example for integration on the boundary, or interfaces between
+ * cells), the FEFaceValues class offers similar functionality as the FEValues
+ * class does for cells. Finally, the FESubfaceValues class offers the
+ * possibility to ingrate on parts of faces if the neighboring cell is refined
+ * and the present cell shares only a part of its face with the neighboring
+ * cell.
+ *
+ * The last member of this group, the UpdateFlags enumeration, is used as an
+ * optimization: instead of letting the FEValues class compute every possible
+ * piece of data relating to a given finite element on a cell, you have to
+ * specify up front which information you are actually interested in. The
+ * UpdateFlags enumeration is used to offer symbolic names denoting what you
+ * want the FEValues class to compute.
+ *
+ * All these classes are used in all tutorial programs from step-3 onward, and
+ * are described there in significant detail.
+ *
* @ingroup feall
*/