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
Quarter
1st month
2nd month
3rd month
1st
January
Mon
Tue
Wed
Thu
Fri
Sat
Sun
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
February
Mon
Tue
Wed
Thu
Fri
Sat
Sun
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
March
Mon
Tue
Wed
Thu
Fri
Sat
Sun
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
2nd
April
Mon
Tue
Wed
Thu
Fri
Sat
Sun
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
May
Mon
Tue
Wed
Thu
Fri
Sat
Sun
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
June
Mon
Tue
Wed
Thu
Fri
Sat
Sun
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
3rd
July
Mon
Tue
Wed
Thu
Fri
Sat
Sun
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
August
Mon
Tue
Wed
Thu
Fri
Sat
Sun
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
September
Mon
Tue
Wed
Thu
Fri
Sat
Sun
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
4th
October
Mon
Tue
Wed
Thu
Fri
Sat
Sun
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
November
Mon
Tue
Wed
Thu
Fri
Sat
Sun
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
December
Mon
Tue
Wed
Thu
Fri
Sat
Sun
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
(The last 7 days of December, shown in grey, are intercalary days that are appended only to the end of leap years.)
