The Fixed Week calendar is a reform of the Gregorian calendar suggested by Bill Hollon. It uses a six-day week in which Saturday and Sunday are merged into a single Sabbath day.
The year has 12 months of the usual names. In a leap year, the even-numbered months have 31 days and the odd-numbered months have 30 days. In common years December has 30 days instead of 31 days. The 31st day of the month is also a Saturday/Sunday, so causing all months to begin on a Monday and have five weeks each.
Bill also suggests using an astronomical leap year rule, which he calls a Generalised Leap Year Rule.