Numerous calendric hieroglyphs of inscriptions at Chichen Itza have been deciphered, with the result that a large body of new material is available for a fresh approach to a solution of the Maya correlation problem. Furthermore, there has appeared a new method of interpreting native time counts which will necessitate revised ideas concerning the chronology of inscriptions, of architecture, of cultural changes, and of historical events at Chichen Itza.
Formerly it was thought that the Maya date 9 Lamat 11 Yax, 13 Tun 1 Ahau meant that the calendar round date 9 Lamat 11 Yax, with a positional determinant 13 Tun 1 Ahau, fell n 13 Tun ending on a day 1 Ahau. This Tun-Ahau method of interpreting a date rested on a fallacy and produced a result irreconcilable with the data. According to the new Katun-Ahau method, the given date, 9 Lamat 11 Yax, fell in a current 13 Tun of a current Katun ending on a day 1 Ahau; this is thoroughly consistent.