 However, the Metonic 19-year lunar cycle which was added to Athanasius’ Festal Letters was a one which had 6 April instead of 5 April.Furthermore, Otto Neugebauer (1899-1990), according to himself, was in the dark about the date of compilation of the whole 7980-year framework (based on the classical Alexandrian 19-year lunar cycle) created by Alexandrian computists.Considering that only around AD 400 Annianus obtained his classical Alexandrian version of the Metonic 19-year lunar cycle by adapting Theophilus’ 19-year lunar cycle by moving its saltus 1 year forward by replacing its date 6 April by 5 April, we may conclude that the compilation in question dates from the fifth century.