These composition sketches by Flemish polyphonists are a great rarity. The folios allow us to look over the shoulder of an anonymous copyist / composer. Thus, these documents teach us that a composer had a total concept in mind and the parties not only came about in succession but also partly simultaneously. At a certain moment even a semi- part score is used. For the knowledge of the composition process this document is in very poor condition and unkempt in writing is of inestimable scientific value. It is also important that the type of the new Parisian chanson makes its appearance in the Low Countries.