This proposal for a notation of the day of the quarter (DOQ) does not change the Gregorian Calendar, but introduce an alternative representation which makes it easier to figure out the day of the week.
Each quarter has a fix number of 91 days (i.e. 13 weeks) except the final mini quarter which may have 1 or 2 days on leap day years. All years start on March 1st, which puts the leap day at the end of the year.
- Q1: March, April, May till 30th
- Q2: 31 May, June, July, August till 29th
- Q3: 30 and 31 August, September, October, November till 28th
- Q4: 29 and 30 November, December, January, February till 27th
- Q5: 28 and eventual 29 February
Examples[]
- 2000-01-01 ⇒ 1999-Q4-34
- 2000-02-27 ⇒ 1999-Q4-91
- 2000-02-28 ⇒ 1999-Q5-01
- 2000-02-29 ⇒ 1999-Q5-02
- 2000-03-01 ⇒ 2000-Q1-01
- 2000-04-01 ⇒ 2000-Q1-32
- 2000-05-31 ⇒ 2000-Q2-01
- 2000-09-01 ⇒ 2000-Q3-03
- 2000-12-31 ⇒ 2000-Q4-33
Advantages[]
- Modulo 7 of day of quarter (DoQ) maps to day of week constantly throughout the year (but varies from year to year). E.g. if Q1-01 this year is Monday then Q2-08, Q3-78, Q4-85, etc are all Monday.
- Modulo 30 of DoQ maps to day of pseudo month of 30,30,31 each quarter.
- Maximum of 91 instead of 366 (ordinal date format) for modulo operation which is not too hard for mental calculation.
- Each date in the Gregorian calendar has a corresponding date in this proposal, most holidays remains the same.
- Does not rely on Gregorian calendar to determine when to start a year like ISO weekly calendar.
- Shorter digit string needed to represent the date compared to most monthly calendars. E.g. November 31st is represented with (Q)3-91 rather than 11-28.
Disadvantages[]
- Not as straight forward as other weekly calendars when it comes to figuring out the day of the week.
- Additional mini quarter, Q5.
- The first two months of the (month-based) year belong to the previous (quarter-based) year, thus the majority of days of that quarter belong to the later year but it itself belongs to the earlier year. This is incompatible with established ISO 8601 rules, e.g. regarding the first and last week of the year.