This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
An observance rule entry records a specific, named holy day or observance together with the precise rule that fixes its date each year, a fixed calendar date, a lunar or lunisolar reckoning, or an offset counted from another observance such as Easter, distinct from the observance's own religious meaning, which the atlas records under the observance's own separate entry. The reference volume Religious Celebrations catalogs holidays, festivals and solemn observances across many traditions specifically by how each one is dated and what practice marks it, treating the dating rule itself as a documented fact worth recording precisely.
An entry records an observance's governing calendar, whether Gregorian, lunar Hijri, lunisolar Hebrew or another system entirely, its stated date or offset within that calendar, and which communities actually follow that rule, since the same named observance is very often dated differently by different branches of the same tradition, or under two different calendars entirely.
Where an observance carries more than one live rule, an older reckoning alongside a reformed one, or a Western date beside an Orthodox date for the same feast, the entry records both honestly as documented, currently followed rules rather than treating one as the sole correct answer.