DIFF Subgroup
H03H 9/0004 Full Title
Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators (electro-acoustic transducers such as loudspeakers, microphones or gramophone pick-ups H04R; piezoelectric, electrostrictive or magnetostrictive devices with mechanical input or output, e.g. actuators or sensors, H10N30/00, H10N35/00)
Of 2 combined children, 0 exist in both systems.
2 codes are CPC-only extensions.