Enharmonic scale
In music theory, an enharmonic scale is an ancient Greek musical scale which contains four notes tuned to approximately quarter tone pitches, bracketed (as pairs) between four fixed pitches. For example, in modern microtonal notation, one of the several enharmonic scales aligned with the conventional key of C major would be C (0 ¢), D (400 ¢), E (450 ¢), F (500 ¢), G (700 ¢), A (1000 ¢), B(1150 ¢), c′ (1200 ¢).