How the comparison is made

• The date as written: the day, month and year are read exactly as the source states them. When the text gives no year, the year of the researched date is used, and the same number is read in both calendars.
• "Seven remaining": the sources count the remaining nights in two ways — with the present night or without it — so the day is the month's length minus seven, or one day after that. Whichever is closer to the text's weekday is accepted, equally in both calendars.
• The verdict: the difference between the weekday in the text and the weekday the date falls on — no difference is an exact match, one day is near, two days or more is a mismatch.
• Several reports: when the sources disagree, the report that fits The Creator's Calendar is shown for events 1–73, and the one that fits the Lunar Hijri calendar after them; every other report appears under "Other reports" with its own verdict.
• Not included: eclipses of the sun and the moon, and events whose source gives no day-level date (the Battle of Mu'tah, the death of Heraclius).
• The researched date is the date recorded for the event on the site after study; it is shown for reference and does not enter the verdict — except for the year, as explained next.
• A different year: the reports of this era disagree widely on the year of an event — the killing of al-Husayn, for example, is dated to different years in different reports. The researched year comes from linking each event with the events before and after it. So when the text does not match in its own year, the same day and month are read in the researched year, in the calendar the research was done in (The Creator's Calendar for events 1–73, the Lunar Hijri calendar after them): no difference is a match, different year, one day is near, different year. Both are counted separately from the matches by the text's own year. The Lunar Hijri calendar has no researched date for events 1–73, so it receives no such verdict there.

Why does not every event match exactly?

1. Fixing the first day of the month: the start of a month could differ by a day from one place or reckoning to another, which moves the day of the month by one against its weekday.
2. The narrator's error: a report may preserve the weekday correctly and slip in the day number, the month or the year — or the reverse — as it passed from narrator to narrator.
3. "The night precedes the day": in the narrators' time it was held that the night comes before its day, so "the night of Friday" was the evening before Friday. This contradicts the Qur'an: nor does the night outstrip the day [Ya-Sin 36:40], and He imposed it upon them for seven nights and eight days in succession [Al-Haqqah 69:7] — seven nights between eight days, so the punishment began with a day and ended with a day, and the night follows its day. In The Creator's Calendar the day begins at dawn and its night follows it. Reports marked night are compared with the day the text names, as written, so some of them appear as near.