The earliest explicit example of fauxbourdon may be in the manuscript "I-BC Q15" ("Bologna, Museo Internazionale e Biblioteca della Musica, MS Q15"), compiled around 1435, which contains several examples, including one by Dufay dating probably to around 1430. Since many early 15th century compositions are anonymous, and dating is often problematic, exact determination of the authorship of the earliest fauxbourdon is difficult. Dufay's contribution to this collection contains the first actual use of the term, in the closing part of his "Missa Sancti Jacobi". It is possible that his use of the word "bourdon" was intended as a pun on St. James' "staff" (which Dufay, or the copyist, drew in miniature above the music). Cividale, Museo Civico MS 101 has a work "O salutaris hostia" (f. 82v) which seems to be a work of fauxbourdon, but not labelled as such.