Scolica enchiriadis is an anonymous ninth-century music theory treatise and commentary on its companion work, the Musica enchiriadis. These treatises were once attributed to Hucbald, but this is no longer accepted. The scale used in the work, which is based on a system of tetrachords, appears to have been created solely for use in the work itself rather than taken from actual musical practice. The treatise also uses a very rare system of notation, known as Daseian notation. This notation has a number of figures which are rotated ninety degrees to represent different pitches.