The fourth volume examines all the works attributed to masters with provisional names from the 1470s to the first half of the 16th century (Master of the Joseph Sequence, Master of the Magdalen Legend, Master of the Orsoy Altarpiece, Master of the Saint Barbara Legend, Master of the Saint Catherine Legend, Master of the Saint Lucy Legend, Master of the Saint Ursula Legend, Master of the View of Saint-Gudule, Master of 1473). It was towards 1900 that anonymous works were first grouped, on the basis of stylistic affinities, around certain paintings presenting particular characteristics. Each group is attributed to an anonymous master named after the painting (the eponymous work) which forms the basis for this group. These ensembles serve to give direction to the work of art historians, in the hope of identifying these anonymous painters at a later date. Some of these groups, to which new works have been added over past decades, appear fairly heterogeneous, and merit critical reexamination in the light of modern analysis methods.