This page uses content from the English Wikipedia. The original article was at Symmetry010 Calendar. The list of authors can be seen in the page history. As with the Calendar Wikia, the text of Wikipedia is available under Creative Commons License. See Wikia:Licensing.
The Symmetry010 Calendar (Sym010) is a proposal for Gregoriancalendar reform developed by Dr. Irv Bromberg of the University of Toronto, Canada.
It is a perpetual solar calendar that conserves the traditional 7-day week, and has symmetrical equal quarters of 30+31+30 days each. Unlike its sibling system and successor, the Symmetry454 Calendar, it does not start every month on Monday, but has month lengths closer to the traditional ones.
It is retained as an alternative for those who think that the Sym454 design is too "radical" a departure from the Gregorian calendar format.
In a leap year, the Symmetry010 leap week is either appended to December, making it a 37-day month, or it can stand alone at the end of the year as a 13th "mini-month" that was dubbed "Irvember" by Yoel Berznoger of Toronto.
The Symmetry010 calendar is demonstrable in Kalendis by choosing 30+31+30 quarter structure in the Symmetry calendar window. The user can also choose the desired handling of the leap week from the "Symmetry Leap Week" submenu of the "Options" menu. The Sym010 calendar arithmetic is also documented in the public domain, alongside that of the Sym454 calendar.
Symmetry010 year layout by quarter
Quarter
1st month
2nd month
3rd month
Q1
January
Week
Mon
Tue
Wed
Thu
Fri
Sat
Sun
W1
01
02
03
04
05
06
07
W2
08
09
10
11
12
13
14
W3
15
16
17
18
19
20
21
W4
22
23
24
25
26
27
28
W5
29
30
February
Week
Mon
Tue
Wed
Thu
Fri
Sat
Sun
W1
01
02
03
04
05
W2
06
07
08
09
10
11
12
W3
13
14
15
16
17
18
19
W4
20
21
22
23
24
25
26
W5
27
28
29
30
31
March
Week
Mon
Tue
Wed
Thu
Fri
Sat
Sun
W1
01
02
W2
03
04
05
06
07
08
09
W3
10
11
12
13
14
15
16
W4
17
18
19
20
21
22
23
W5
24
25
26
27
28
29
30
Q2
April
Week
Mon
Tue
Wed
Thu
Fri
Sat
Sun
W1
01
02
03
04
05
06
07
W2
08
09
10
11
12
13
14
W3
15
16
17
18
19
20
21
W4
22
23
24
25
26
27
28
W5
29
30
May
Week
Mon
Tue
Wed
Thu
Fri
Sat
Sun
W1
01
02
03
04
05
W2
06
07
08
09
10
11
12
W3
13
14
15
16
17
18
19
W4
20
21
22
23
24
25
26
W5
27
28
29
30
31
June
Week
Mon
Tue
Wed
Thu
Fri
Sat
Sun
W1
01
02
W2
03
04
05
06
07
08
09
W3
10
11
12
13
14
15
16
W4
17
18
19
20
21
22
23
W5
24
25
26
27
28
29
30
Q3
July
Week
Mon
Tue
Wed
Thu
Fri
Sat
Sun
W1
01
02
03
04
05
06
07
W2
08
09
10
11
12
13
14
W3
15
16
17
18
19
20
21
W4
22
23
24
25
26
27
28
W5
29
30
August
Week
Mon
Tue
Wed
Thu
Fri
Sat
Sun
W1
01
02
03
04
05
W2
06
07
08
09
10
11
12
W3
13
14
15
16
17
18
19
W4
20
21
22
23
24
25
26
W5
27
28
29
30
31
September
Week
Mon
Tue
Wed
Thu
Fri
Sat
Sun
W1
01
02
W2
03
04
05
06
07
08
09
W3
10
11
12
13
14
15
16
W4
17
18
19
20
21
22
23
W5
24
25
26
27
28
29
30
Q4
October
Week
Mon
Tue
Wed
Thu
Fri
Sat
Sun
W1
01
02
03
04
05
06
07
W2
08
09
10
11
12
13
14
W3
15
16
17
18
19
20
21
W4
22
23
24
25
26
27
28
W5
29
30
November
Week
Mon
Tue
Wed
Thu
Fri
Sat
Sun
W1
01
02
03
04
05
W2
06
07
08
09
10
11
12
W3
13
14
15
16
17
18
19
W4
20
21
22
23
24
25
26
W5
27
28
29
30
31
December
Week
Mon
Tue
Wed
Thu
Fri
Sat
Sun
W1
01
02
W2
03
04
05
06
07
08
09
W3
10
11
12
13
14
15
16
W4
17
18
19
20
21
22
23
W5
24
25
26
27
28
29
30
W7
leap week
(Days 31 through 37 of December are intercalary days that are appended only to the end of leap years.)
Background[]
Balanced quarters are desirable for businesses because they aid in fiscal planning and analysis.
All holidays, birthdays, anniversaries, etc. are permanently fixed.
All ordinal day and week numbers within the year are also permanently fixed.