Tam Tai, Kim Lau and Hoang Oc by birth year and year in question

采用的约定

These three are folk conventions, not measurements, and they disagree in exactly two places. First, LUNAR AGE: this table takes it as year in question minus birth year plus one, the most common Vietnamese reckoning, while some schools count lunar years elapsed since the new year. For anyone born between 1 January and the lunar new year the two give different numbers. Second, BIRTH YEAR: the nam_sinh column here is a solar year, while Tam Tai is judged by the branch of the lunar year, so anyone born before the lunar new year belongs to the previous lunar year. The ghi_chu column marks those rows. This table does not say a year is good or bad; it says only whether the pair falls into those three groupings.