The name of a lunar month, occurring about September to October, following the month Okalna.
There are twelve lunar months in the Batad Ifugao calendar, constituting a lunar year. This is almost eleven days short of a solar year. The discrepancy is adjusted by adding an extra lunar month every second or third year. On these years, the month Datto' is repeated, the second called Miyadwah Datto' Second Datto'. Second Datto' is added on a year when the beginning of the lunar month, occurs near the beginning of September of the Gregorian calendar. This is determined by noting that arrow grass, bilāu, blooms near the end of the lunar month or during the month Ohyab. The extra month will assure that the following year the arrow grass will bloom at the beginning of Datto'. If the discrepancy is more than one lunar month, an additional month, Miyatluh Datto', is added. When months are added, this month is called Hopap di Datto' First Datto'. During this month men and women typically work at tasks not related to agriculture. As needed, women weed the second-crop rice fields.