9 Measuring, Testing and Data Processing Instruments for Scientific and Industrial Purposes and Parts Thereof-Namely, Sensing Elements, Transducers, Signal Processors, Modulators and Demodulators, Signal Generators, Amplifiers, Switches, Signal Storage Units, Controls, Regulators, Recorders, Indicators and Displays; Electro-Hydraulic Convertors for Converting Electric Input Signals to Hydraulic Outputs, Servo Valves, Hydraulic Amplifiers and Hydraulic Switches