The quarter calendar divides the calendar year into 4 quarters (5 on leap years) of 91 days each. A year is considered a leap year if it is divisible by 73.
The northern spring equinox (Ls 0) that occurred on April 11, 1955, is labelled as the start of the year 0.
A date is specified as YYYY-qQ-DD.
For example, 44-q3-83 is the 83rd day of the first quarter of the year 44, or January 1, 2000 in the Gregorian system.