Complex sentence: Harmonic fragment scales form a rare exception to this issue-such as 1:1 9:8 5:4 11:8 3:2 7:4 15:8 2:1, all the pitches are from the harmonic series, so intervals are perfect.
Split into simpler sentences: Harmonic fragment scales form a rare exception to this issue. In tunings such as 1:1 9:8 5:4 11:8 3:2 7:4 15:8 2:1, all the pitches are chosen from the harmonic series, so all the intervals are perfect.