An active EMI shield for protecting medical instruments from mobile RF emitters uses RFID tags and tag readers to facilitate identification of an RF emitter entering the EMI shield. A tape system includes a tape head with two read elements associated with each data track to be simultaneously read. The table also includes two tensionable platform cable members and a pair of platform-to-cable load transfer bars. The first nonmagnetic spacer layer resides between the first pinned and free layers. Fuels for the attached engine may thereby be varied or substituted by adjusting the engine peak pressure and compression to one adequate for the chosen fuel.