What does ‘x self’ mean

[Fairorchids]

Correction: 'x self' = pollen from same plant, or possibly from a plant that is a natural division of the same plant.

If it is a clone (meristem propagated plant), it cannot be considered 100.000% identical, especially if it is a 2nd or 3rd round propagation, due to the random mutations that can occur with that form for propagation. In that scenario I would judge it to be 'x sib' (for sibling).

Yes, this is splitting hairs, as in both cases the offspring remains a true species.