This encoding (NRZI: Non Return to Zero Inverted on one) foresees a transition for the bits to 1, to half of the bit, and no transition for the bits to zero. The transition for the bits to '1' can be 'high-low' or 'low-high' according to the state of the signal in the previous bit. As to the NRZ the synchronization problem is solved, unless meeting long sequences of '0'. It is used in the FDDI networks on fiber optics.