I've missed the interesting discussions here for awhile, have been working on orchestral things. But working again on this little piece with an organ part designed to fit with a choir in my version of just intonation.
Continousbass, no, I expect equal tempered. And not perfectly in tune! The focus of the simple organ part was to use 'out-of-tune' notes only as decorative momentary notes, to avoid, especially, trampling on the bass voice when it has a third, and to give as much support as possible with notes that are very close in pitch whether just or equal.
ghmus7, yes. I'm working on yet another appendix describing the symbols, but basically the filled triangle is the pure harmonic major third or its relatives, the light up and down arrows pythagorean fifth relations (which, generally, are close in pitch to equal temperament, though farther away the farther along the circle of fifths you go), and the up open triangle a high tuned minor third or relative.
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