Calendar Basis of Early Regnal Year Notations
Determine whether the regnal year notations attested from the beginning of the First Dynasty were structured according to a lunar calendar or the Egyptian civil calendar, to establish the calendrical framework underlying early Egyptian administrative records.
References
It is not possible to tell if the years were lunar or of a civil calendar.
— Timekeeping at Akhet Khufu, as shown by the Diary of Merer
(2411.08061 - Sparavigna, 2024) in Section Turn about (phr) Cattle Count (discussion of Spalinger, 2018)