Octave species various available intervals could be combined in any order, even restricting species to just the diatonic genus would result in twelve ways of dividing the octave (and his 17th-century editor, Marcus Meibom, pointed out that the actual number is 21), but "only seven species or forms are melodic and symphonic" . Those octave species that cannot be mapped onto the system are therefore rejected . In chant theory beginning in the 9th century, the "New Exposition" of the composite treatise called "Alia musica" developed an eightfold modal system from the seven diatonic octave species of ancient Greek theory, transmitted to
Uilleann pipes soft D and is accomplished by applying slightly more pressure to the bag and flicking a higher note finger as it is sounded. Pipemakers tune the chanter so the hard D is the in-tune note, the soft D usually being slightly flat. Many chanters are fitted with keys to allow accurate playing of all the semitones of the scale. Four keys will give all the semitones: F, G, B, C. Older chanters usually had another key for producing D (D in the third octave), and often another small key for E, and another for D (as opposed to the E