Natural focal plane
The natural focal plane refers to zero (plano) correction. Note that plano lenses might have quality issues, so it is recommended not to wear plano glasses or contacts, except plano (no correction) sunglasses.
Differentials
Natural focal plane is used as differentials in some cases of low myopia.
Normalized
Natural focal plane is used along with normalized by alternating between zero and normalized/full correction in some cases of low myopia.
At emmetropia, the natural focal plane is full correction.
Zero Diopter Reset
Natural focal plane is used for zero diopter resets, except in cases of high myopia, for which differentials are used.