 The abbreviation CR stands for Cauchy–Riemann or Complex-Real.The notion of a CR structure attempts to describe "intrinsically" the property of being a hypersurface (or certain real submanifolds of higher codimension) in complex space by studying the properties of holomorphic vector fields which are tangent to the hypersurface.Suppose for instance that "M" is the hypersurface of formula_4 given by the equation

where "z" and "w" are the usual complex coordinates on formula_4.