“…In the pure General Relativity it is impossible to specify the generation procedure in the above mentioned sense because, in fact, there exists only a one-parametric charging symmetry transformation whose 'specification' leads to an identical map. This transformation coincides with the Ehlers symmetry which must be 'normalized' to preserve the asymptotical flatness property, see, for example, [21], where this material together with its straightforward generalization to the string theory case is considered in details. Note that in our approach all the classical nonlinear symmetries (like the Ehlers and Harrison transformations) arise in a matrix-valued framework; nevertheless it is possible to identify some string theory symmetries as the Harrison and Ehlers maps in the conventional non-matrix sense, see [34], [35].…”