There are 3 types of polarity for MTP/MPO fiber cables:
Type A/ Method A: Straight,
Type B/ Method B: Reversed
Type C/ Method C: Pars Flipped
Type A/ Method A MPO-MPO fiber cables is straight-through. One end with the key pointing up and the other end with the key point facing down. This allows the fibers at both ends of the cable to have the same fiber position. For example, a fiber at position 1 (P1) on one side of the connector will go to P1 on the other side of the connector.
Type B/ Method B MPO-MPO fiber cables is reversed in pair, use keyed connectors at both ends of the cable. This type of array matching results in inversion, which means that the fiber positions are reversed at each end. The P1 fiber at one end is paired with the P12 fiber at the other end.
Type C/ Method C MPO-MPO fiber cables is pairs flippped cable. The position of core P1 at one end is P2 at the other end, and the position of core P2 at one end is P1 at the other end, and the positioning key at one end faces up, with one end of the positioning key facing down.