pitch class

12.09  pitch class. That attribute of a tone which defines its position within the octave. Pitch classes are referred to by note names (C, C#, D, etc.).

Annotation 1          Tones of the same pitch class but that differ in pitch height are in some sense perceptually equivalent, and are given the same name, see 12.14 and Table 3.

Annotation 2          For example, {C_n : n is an integer} = {…, C_-2, C_-1, C₀, C₁, C₂, C₃ …} is the C pitch class.