 Since a chromatic scale is formed by 12 pitches (each a semitone apart from its neighbors), it contains 12 distinct tritones, each starting from a different pitch and spanning six semitones.According to a complex but widely used naming convention, six of them are classified as "augmented fourths", and the other six as "diminished fifths".Under that convention, a "fourth" is an interval encompassing four staff positions, while a "fifth" encompasses five staff positions (see interval number for more details).