 Although the standard modern version of this chant has seventeen notes for the first four words, late medieval chant books such as the ones used in Florence in the early 15th century, have only fourteen notes.These fourteen notes are used as a canonic "color" in the two tenors, with an interlocking "talea" pattern (the rhythm patterns of the two tenor parts are different from each other) that totals 28 longa notes, of which the first 14 are rests.This interlocked pair of tenor parts is stated four times, following a diminution scheme in which the identical notation is interpreted under four different mensuration signs, first in "tempus perfectum" in "integer valor" (each "longa" transcribed as a 6/2 bar), then in "tempus imperfectum" in "integer valor" (transcribed as 4/2), then in "tempus imperfectum diminutum" (4/4), and finally in "tempus perfectum diminutum" (6/4), resulting in total length proportions of 6