The Supplementary hypothesis can be seen as yet another evolution of Wellhausen's theory that solidified in the 1970s. Proponents of this view assert three sources for the Pentateuch: the Deuteronomist as the oldest source, the Elohist as the central core document, with a number of fragments or independent sources as the third. Deuteronomy is seen as a single coherent document with a uniformity of style and language in spite of also having different literary strata. This observation led to the idea there was such a thing as a "Deuteronomist school" that had originally edited and kept the document updated. This meant the supplementary model became the literary model most widely agreed upon for Deuteronomy, which then supports its application to the remainder of the Pentateuch as well.