The book was compiled from a pre-existing collection of nine charter groups, originally entered in Gospel Books, and appears to have been produced to help in Bishop Urban's diocesan boundary disputes with the dioceses of St David's and Hereford. Many of the supposed early charters have therefore been 'edited' to serve Llandaff's interests. They are also undated and many are corrupt. However, through her exhaustive study of these documents, Professor Wendy Davies has reconstructed much of the original text and calculated probable time-frames. This work has been accepted by most historians, but criticized in some non-academic quarters.