Bent Ficta Version
This ficta version is based on Margaret Bent’s “Diatonic Ficta” article from Early Music History 4 (1984). It’s based on the notion that all tritones and diminished 5ths should be corrected to perfect intervals.
Urquhart Ficta Version
This version is from Peter Urquhart’s paper, “Do not untune the sky” from AMS-New York (1995). It is based on his notion that cross-relations should be allowed to occur whenever the choice of ficta by linear criteria creates them in the vertical texture. This is especially noticeable at m. 24. Urquhart’s approach is to make ficta decisions based on what a single performer reading a part (i.e., not a score) might do on first reading.
Duffin Ficta Version
This version is based on my own edition of this motet (Fazer Editions, 1992). It takes a longer view of the phrase direction in the bass part (as the crux of the linear tritone issue) as it rises from E up to middle C. It also allows a B-natural in the bass at the beginning of the 3rd measure as perfectly within the style of the time.