Here is a sample of the nuance notation. The words of the Gradual “Viderunt omnes” (for Christmas Day) and the melody in traditional “square notation” are taken from the Vatican Graduale (1908). Over the staff I have entered in my own hand the nuance notation as available in the photofacsimile of Laon MS 239 in Paleographie musicale XI, also digitized online, and in Graduale triplex
(1979); these sources are all cited in Resources of About the Archive. My hand copy is only for illustration here; the hand copies by Marie Claire Billecocq and Rupert Fischer in Graduale triplex should be used for singing and study.