In music theory

Music theory

Music theory is the study of how music works. It examines the language and notation of music. It seeks to identify patterns and structures in composers' techniques across or within genres, styles, or historical periods...

, is, at its simplest, "a chromatic scale

Chromatic scale

The chromatic scale is a musical scale with twelve pitches, each a semitone apart. On a modern piano or other equal-tempered instrument, all the half steps are the same size...

 with each tone

Note

In music, the term note has two primary meanings:#A sign used in musical notation to represent the relative duration and pitch of a sound;#A pitched sound itself....

 written in manifold notation

Musical notation

Music notation or musical notation is any system that represents aurally perceived music, through the use of written symbols.-History:...

". Relatedly, the enharmonic scale is, "an [imaginary] gradual progression by quarter tones," or any, "[musical] scale

Musical scale

In music, a scale is a sequence of musical notes in ascending and descending order. Most commonly, especially in the context of the common practice period, the notes of a scale will belong to a single key, thus providing material for or being used to conveniently represent part or all of a musical...

 proceeding by quarter tone

Quarter tone

A quarter tone , is a pitch halfway between the usual notes of a chromatic scale, an interval about half as wide as a semitone, which is half a whole tone....

s". More properly dieses or 'divisions', nonexistent on modern keyboards

Musical keyboard

A musical keyboard is the set of adjacent depressible levers or keys on a musical instrument, particularly the piano. Keyboards typically contain keys for playing the twelve notes of the Western musical scale, with a combination of larger, longer keys and smaller, shorter keys that repeats at the...

 and originating in the diminished seventh chord

Diminished seventh chord

A diminished seventh chord is a four note chord that comprises a diminished triad plus the interval of a diminished seventh above the root. Thus it is , or enharmonically , of any major scale; for example, C diminished-seventh would be , or enharmonically...

. More broadly, an enharmonic scale is a scale in which (using traditional notation) there is no exact equivalence between a sharpened

Sharp (music)

In music, sharp, dièse , or diesis means higher in pitch and the sharp symbol raises a note by a half tone. Intonation may be flat, sharp, or both, successively or simultaneously...

 note and the flattened note it is enharmonic

Enharmonic

In modern musical notation and tuning, an enharmonic equivalent is a note , interval , or key signature which is equivalent to some other note, interval, or key signature, but "spelled", or named, differently...

ally related to, such as in the quarter tone scale.
As an example, F sharp and G flat are generally equivalent in a chromatic scale, but they would be distinguished in an enharmonic scale.