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The switch approach places twelve contacts somewhere on the palm or thumb side of the phalanges and one the tip of the thumb. These permit detection of a thumbcode and identification of the thumbed phalanx. In addition three switches are placed one between each adjacent pair of fingers, permitting identification of the closure.

The twelve finger contacts call for twelve wires leading from the hand to the encoding device, and the interdigit switches an additional four assuming a common ground. That ground can also connect to the thumb, for a total of fifteen signal wires and one common ground.