What do terms mean in the Chord Function area when I pull down the dividing line below the Chord Area ?
Terms you see at the Chord Function area, such as Diatonic, Sub V7, etc. represent groups of Chords that include respective Chord Functions. For example, if you select Diatonic, you’ll see some Chords closely related to diatonic such as Sub Dominant Minor Chords besides purely diatonic chords. The Chord Function, Sec.Dominant, includes Extended Dominant Chords and their related II-7 besides purely Secondary Dominant Chords.