[randomswede]

ETA: Ahaha, I managed to read "days" as "weekdays". The following is now. permanent marker of my reading incomprehension.

IIRC (and it's been a while, so I may well not RC), specifies that 1 is Monday, 2 is Tuesday, ..., 6 is Saturday and both 0 and 7 are Sunday. And the reason that looks weird is that there is (IIUC) a genuine difference between western nations as to if a week starts o Sunday or Monday.

Which, you know, sucks. But, also makes it somewhat easy to make a C array that you can index with a (.tm_wday%7) to easily get the day of the week.

Which may also be the reason why months start at 0.