The Quinta Calendar is a proposed calendar invented by 'Duncan McGregor' that uses a 5-day week called a Quinta and each year has a whole number of these Quintas.
The calendar year has 12 months (January to December) each of 30 days equal to 6 quintas. The first month (January) is preceeded by a single quinta called Yule. Leap years have a leap quinta after the last month (December)
Leap Year Rule
The leap year rule is one of two suggested by Karl Palmen. Every year whose number is divisible by 20 is a leap year, unless its number is also divisible by 640. The resulting mean year is 365.2421875 days.
The new year is intended to occur close to the northern winter solstice. The 21 December 1968 is suggested as the first day of year 0 Anno Spatii. Negative numbers would be used for earlier years.