The label “Neapolitan” is used in classical music for the ♭$$\left.\text{II}\right.$$ chord and is labeled as “$$\left.\text{N}\right.$$” instead of ♭$$\left.\text{II}\right.$$. For example, when the Neapolitan chord occurs in first inversion—its most common inversion—it is labeled as $$\left.\text{N}^{6}\right.$$.
Being a chromatically altered $$\left.\text{ii}\right.$$ chord, the Neapolitan has pre–dominant harmonic function.