The bridge contains two independent measurement systems, a 2-point system with 4 external channels, and a 4-point system with 6 external channels.
Each system is able to measure inductors, capacitors and resistors, but only the 4-point system is suited for measuring mutual inductors.
The 2-point system is best suited for measuring high impedances, especially small capacitors, as the wiring capacity is canceled out.
The 4-point system may be used with or without input transformer. With transformer low impedances and mutual inductances may be measured with a very low noise. High resistor values must be measured without input transformer to obtain the lowest noise.