From the Buxheimer Orgelbuch (c. 1450). Three sections, and my best guess is that there is a Kyrie chant in the pedals. The LH seems to form a bass, the RH has filigree decoration. I have no idea how authentic the registration might be, but it makes sense of how I read the music.
Pedal - 8' Principal
LH - 16' Bourdon and 8' SD
RH - 8' Flute and 2 2/3' Nazard