Such a hierarchy would be important since the data base on amino acid sequences of proteins delivers only scant information on the functions and spatial structures of these proteins, apart from the recognition of some putative active sites of enzymes and hints about their location.Therefore, additional information from a new source would be desirable to classify the nature of the proteins and to test suppositions from sequences.The approach chosen was to use the temperature factors that are measured in diffraction experiments.The temperature factor of a given atom is a measure of the diameter of its volume of occupancy and hence of the extent of its vibrations.