https://en.wikipedia.org/wiki/ISO_week_date
A precise date is specified by the ISO week-numbering year in the format YYYY, a week number in the format ww prefixed by the letter 'W', and the weekday number, a digit d from 1 through 7, beginning with Monday and ending with Sunday. For example, the Gregorian date Sunday, 20 November 2022 corresponds to day number 7 in the week number 46 of 2022, and is written …