Or just a 13 month calendar of 28 days each, plus a floating "year day" and "leap day" that aren't a part of any week or given any week day designation. https:

Or just a 13 month calendar of 28 days each, plus a floating "year day" and "leap day" that aren't a part of any week or given any week day designation. https://en.wikipedia.org/wiki/International_Fixed_Calendar https://en.wikipedia.org/wiki/International_Fixed_Calendar