EXFO FTB-635 Wideband Copper and DSL Test Module - Manual (Page 176)

Multimeter Tests
168 FTB-635
Balance Test
Summary
Balance is the best single indicator of pair condition, by assessing how
much noise the pair is cancelling or mitigating. Many cables are
constructed to mitigate 60dB of noise, which the test displays directly. The
Passive test measures Power Influence, VF Noise and calculates the
difference; but this method depends on the presence of at least 60dB of
Power Influence. The active test applies it's own signal or noise and can be
used anytime or when there is not enough Power Influence present for the
Passive test.
Summary tab displays the pass/fail status of the tests executed. Refer
Copper Tests: Result Summary on page 291 for more information.