Talk:ISO week date

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—Yamara ✉ 18:18, 14 February 2008 (UTC)
thread_title:  [[Wikipedia:WikiProject_Time/Assessment|WikiProject Time assessment rating]] comment 

message: Ok, I understand now "What if most years had a leap week?". What matters for the maximum change of corresponding equinoxes between two years is the largest deviation of a year from the average year.--Patrick 21:38, 30 May 2006 (UTC)
thread_title: Discussion

message: I would situate the following sentence at the beginning:
The first week of a year is the week that contains the first Thursday of the year. It is also (equivalently) the week containing the 4th day of January.
Everybody looks for that information and has to read half a page to get to it.
Currently prior we talk about iso.
Well, that´s scientific correct, but I think people look for a trivial explanation first and than for the scientific one. My opinion of course br hans.stangl@gmx.at
--194.113.154.132 (talk) 08:15, 26 February 2014 (UTC)
replies: text: Huh? It’s in the lede, after all, not buried in some section. Also, not every read of this article is primarily looking for that piece of information. Nevertheless, I rearranged and rephrased the introduction today and the Thursday rule moved up a bit. — Christoph Päper 20:10, 26 February 2014 (UTC)
replies: text:  I wasn't looking for it, I was just reading generally about ISO 8601 to see whether it might be useful in a project. I found the first mention ("and, hence, 4 January") a bit too terse and not obvious just from reading it. I added always contains, which, for me, improves the readability, though one might quibble about redundancy. I also added a link to where it's explained for those with a similar "Eh?" response.  92.0.230.198 (talk)   — Preceding undated comment added 13:14, 17 January 2015 (UTC)
thread_title:  Lede 

message: I have seen ISO 8601:2000 but not ISO 8601:2004.  ISO 8601:2000 does not use the term "leap week"; I don't know whether ISO 8601:2004 does.
Unless the term is introduced in ISO 8601:2004, it seems to me unwise to introduce it elsewhere; "week 53" suffices.  It leads to using "leap year" for 53-week years, which clashes with conventional use.  It might be thought to mean a week containing February 29th.
Re section "Disadvantages" : The ISO Week Calendar could fully replace the Gregorian, because it is possible to calculate Day 1 of a given year directly - but the expression will be more complicated.
Re section "Advantages" : Although the date of Easter Sunday would be no easier to calculate, the number of possible dates would be less, since all are Day 7.  Only a few Week Numbers would be possible.
82.163.24.100 13:45, 30 January 2007 (UTC)
replies: text: The page now mostly uses long year to refer to years with 53 weeks. — Christoph Päper 18:22, 9 August 2010 (UTC)

text: Really? You could have just edited it (which I’ve done now instead) There were four instances of “leap week”, two of which did not specifically relate to ISO terminology. — Christoph Päper 07:56, 13 September 2016 (UTC)
replies: text:  I think the article should still mention that it is (effectively) a leap week calendar, but need not give it the prominence it currently enjoys. Karl (talk) 11:42, 13 September 2016 (UTC)
replies: text:  I stopped reading, had a quiet chuckle, thought "what a terrible article this is", came to the talk page to see if anyone else was of the same mind, wrote this, and left. That'll teach me to click on W***ypedia links.  — Preceding unsigned comment added by 194.228.59.158 (talk) 22:35, 25 August 2017 (UTC)
thread_title:  Use of term "Leap Week" 

message: I stopped reading this article when I saw "leap week" followed by the comment that it isn't in the standard. It needs to be edited out or the article delelete completely - Wikipedia is not a place for original research or soapboxing.114.198.81.18 (talk) 09:41, 11 September 2016 (UTC)
replies: text: Really? You could have just edited it (which I’ve done now instead) There were four instances of “leap week”, two of which did not specifically relate to ISO terminology. — Christoph Päper 07:56, 13 September 2016 (UTC)
replies: text:  I think the article should still mention that it is (effectively) a leap week calendar, but need not give it the prominence it currently enjoys. Karl (talk) 11:42, 13 September 2016 (UTC)
replies: text:  I stopped reading, had a quiet chuckle, thought "what a terrible article this is", came to the talk page to see if anyone else was of the same mind, wrote this, and left. That'll teach me to click on W***ypedia links.  — Preceding unsigned comment added by 194.228.59.158 (talk) 22:35, 25 August 2017 (UTC)
thread_title: 2016-2017

message: * Template:ISOWEEKDATE -  The opposite function of 
:* Template:ISOYEAR - 
:* Template:ISOWEEK - 
:* Template:ISOWEEKDAY - 
* Template:ISOWEEKDATE2YMD -  The opposite function of 
:* Template:ISOWEEKDATE2Y - 
:* Template:ISOWEEKDATE2M - 
:* Template:ISOWEEKDATE2D - 
:(unsigned date unknown)
Use the  parser function instead. JIMp talk·cont 07:26, 1 June 2012 (UTC)
thread_title:  Templates 

message: I don't get this part: "It cannot replace the Gregorian calendar, because it relies on it to define the new year day (Week 1 Day 1)."
Is what you want to say that if it coexists with the Gregorian Calendar then it has to be decided which one of them that tells when to celebrate new year's eve  since the days for a new year differs?
I can see no logical reason to why new year couldn't be defined as Week 1 Day 1. I mean it's pretty much how it is now with the leap days, we don't celebrate the new year on different times on the day even if it supposedly moves approx 6 hours each year.
--Crouz 20:50, 4 November 2007 (UTC)
replies: text: The Gregorian 400-year cycle is necessary to decide which week and year number the first and last days of a year belong to. That means there is no simple algorithms that decides whether a week-year has a 53rd week based solely on the year number. — Christoph Päper 18:22, 9 August 2010 (UTC)
thread_title:  Disadvantage question 

message: I would like to see a little bit about the calendar's history. When was it first used? And by whom? Who or what agency invented it? For example, the link to years-with-leap-weeks says that the "first" one is 2009. Do they mean the "next" one? Or is the calendar so recent that we haven't had one yet?  —Preceding unsigned comment added by MiguelMunoz (talk • contribs) 01:59, 11 July 2008 (UTC)
replies: text: It's actually fairly similar to some old Nordic/Icelandic calendar variants, which were designed so that each year would contain an integral number of weeks.  However, its modern usage seems to have originated in large industrial corporations which planned their production schedules and payrolls around the work-week. AnonMoos (talk) 00:03, 15 December 2008 (UTC)
thread_title: History

message: The article used Gregorian Year correctly, and used ISO year to mean the yyyy of yyyy-Www-d.  But the yyyy of yyyy-mm-dd is also fully defined in ISO 8601, and has priority.  Alas, ISO offers no convenient term for the week-numbering year. Therefore, I have changed "ISO year" to "ISO week-numbering year" except where the "week" context was strong enough already.
ISO 8601 says nothing about "leap week".  I have changed the article accordingly.  While the term is useful in classifying calendars in accordance with which unit they occasionally insert, there has been in the Article a source of possible confusion in using "leap year" to refer to a 53-week year, because its use to refer to a Jan..Dec containing a Feb 29 is so thouroghly established.  That may need further attention.
For details, see the History page.
82.163.24.100 (talk) 12:49, 22 September 2008 (UTC)
thread_title:  Terminology 

message: I’ve moved the section Calendar cycle to section Weeks per year, after I had added some simple observations on the pattern there. These contradict! Could someone please check the list of years with 53 weeks on the one hand and the cycle calculations with doomsday and dominical letters on the other hand? — Christoph Päper 10:42, 23 March 2011 (UTC)
replies: text: Perhaps see my talk post elsewhere: Talk:Seven-day week#Week numbering systems--Nø (talk) 20:55, 23 March 2011 (UTC)
replies: text:  No, sorry. It is possible that the calendar cycle section was written by someone using the Doomsday algorithm and I don’t know whether it’s valid outside the range 1900–2100. If I remember correctly I was the one that created the list of 53-week years in the Gregorian 400-year cycle, but I can’t find my notes on those calculations. — Christoph Päper 10:15, 24 March 2011 (UTC)
replies: text: I fixed it, "unusual" things can only happen across 100, 200 and 300.--Patrick (talk) 13:22, 24 March 2011 (UTC)
thread_title:  Contradiction in section “Weeks per year” 

message: Why does the article not mention that dates in week-date format are basically incomprehensible to a human viewers? I definitely expected this to be listed in the disadvantages section... 203.206.239.111 (talk) 00:54, 12 May 2011 (UTC)
replies: text: Many businesses work with weekly calendars. For the people working in them the week notation is completely familiar. −Woodstone (talk) 10:46, 12 May 2011 (UTC)

text: Indeed. E.g., in Danish schools, "Wednesday in week 40" may be a far more useful way of identifying a day than "October 5th". For one thing, in a school with a weekly schedule, includng the week-day is most useful, and for another, longer-term scheduling often involves entries like: "Week 38-40: Medieval History", say. In such a context, it is the standard way of giving dates that is nearly incomprehensible. Of course, one may list as a disadvantage of either system that they are mutually incomprehensible (or at least hard to convert mentally - a bit like feet and metres, just worse).--Nø (talk) 14:21, 12 May 2011 (UTC)
thread_title:  Human readability 

message: Article: The ISO 8601 definition for week 01 is the week with the year's first Thursday in it.
There's no mention of why it's Thursday. Was it an arbitrary choice or is there some rationale? As this scheme is about working weeks, why wasn't it the naively obvious candidate, Monday? 92.0.230.198 (talk) 12:53, 17 January 2015 (UTC)
replies: text: Thursday is in the middle of the week. So the majority of the days in each week will belong to the ISO week-numbering year with the same number as their Gregorian year. So a week with three days in 2008 and four days in 2009 will belong to the ISO week-numbering year 2009. And a week with four days in 2009 and three days in 2010 will also belong to the ISO week-numbering year 2009. Boivie (talk) 17:21, 17 January 2015 (UTC)
thread_title:  Why Thursday?

message: Substituted at 20:02, 1 May 2016 (UTC)
thread_title: Assessment comment

message: There’s a section entitled “Dates with fixed week number”. I’m considering to change it in a way that it says something about possible week numbers for all dates not just the ones with 100% or 97% likeliness, but I’m not sure yet whether and how this should be done. 
From January 4 through February 29, all dates fall in one of two weeks of the same year. The probabilities repeat every seven days. If multiplied by 400 (or 97 for Feb29), one gets the absolute occurences per Gregorian leap cycle.
 ISO weeks W01 through W09, January and February
Weeks	Jan04 Jan11 Jan18 Jan25 Feb01 Feb08 Feb15 Feb22 Feb29	Jan05 Jan12 Jan19 Jan26 Feb02 Feb09 Feb16 Feb23	Jan06 Jan13 Jan20 Jan27 Feb03 Feb10 Feb17 Feb24	Jan07 Jan14 Jan21 Jan28 Feb04 Feb11 Feb18 Feb25	Jan08 Jan15 Jan22 Jan29 Feb05 Feb12 Feb19 Feb26	Jan09 Jan16 Jan23 Jan30 Feb06 Feb13 Feb20 Feb27	Jan10 Jan17 Jan24 Jan31 Feb07 Feb14 Feb21 Feb28
W0n  	100%                                                 	85¾%                                           	71½%                                           	57%                                            	43%                                            	28½%                                           	14½%
W0n+1	0%                                                   	14¼%                                           	28½ %                                          	43%                                            	 57%                                           	71½%                                           	85½%
From March 1 till December 28, the ratios change by a tad over 3% due to leap years beginning on a Thursday (DC) which have the Thursday of W09 on February 29, i.e. the only years where 5 weeks belonged to February if one applied the Thursday rule.
 ISO weeks W09 through W52, March to December
Weeks	Mar01 … Dec27	Mar02 … Dec28	Mar03 … Dec22	Mar04 … Dec23	Mar05 … Dec24	Mar06 … Dec25	Mar07 … Dec26
Wn   	96¾%         	82¼%         	68%          	53¾%         	39¼%         	25¼%         	10¾%
Wn+1 	3¼%          	17¾%         	32%          	46¼%         	60¾%         	74¾%         	89¼%
Around New Year, things get a bit more complicated, because the dates December 29 through January 2 can fall in 3 different weeks: W53 usually spans Dec28–Jan03, but in DC years Dec27–Jan02. That means it contains 7 out of 8 possible dates, whereas weeks W01–W08 have a range of 13 possible dates and the rest even 14 dates.
 Dates which can fall in ISO week 53
Week  	Dec27	Dec28	Dec29	Dec30	Dec31	Jan01	Jan02	Jan03	Jan04
W52   	96¾% 	82¼% 	68%  	53¾% 	39¼% 	25¼% 	10¾% 	0%   	0%
W53   	3¼%  	17¾% 	17¾% 	17¾% 	17¾% 	17¾% 	17¾% 	14½% 	 0%
W01   	0%   	 0%  	14¼% 	28½% 	43%  	57%  	71½% 	85½% 	100%
Last  	85½% 	100% 	85¾% 	71½% 	57%  	43%  	28½% 	14½% 	0%
W52/53	100% 	100% 	85¾% 	71½% 	57%  	43%  	28½% 	14½% 	0%
Ordinal days, DDD, are similar to Jan/Feb dates, because the 366th (leap) day is appended at the end of the year. That means, one could provide a simple formula using modulo 7 to get the week number from the three-digit day number. 
Any suggestions or concerns, diagrams, tables or references (besides RH van Gent’s site)? — Christoph Päper 20:15, 4 July 2016 (UTC)
thread_title:  Possible weeks of dates 

message: We should change this title to "Differences" since every Person has a different understanding if this is a Disadvantage. 
--MajorValerian (talk) 13:32, 7 May 2020 (UTC)
thread_title:  "Disadvantages" 

message: From the list of properties of the first week of a year:
:It has the year's first working day in it, if Saturdays, Sundays and 1 January are not working days.
This only works if 2 January is a working day. If 1 January is on a Thursday and 1 and 2 January are off then the first working day will be on Monday, 5 January, which is in Week 2. In some regions 2 January is a holiday, where I live it is Berchtoldstag.
--Adi86 (talk) 14:14, 20 February 2021 (UTC)
thread_title:  First working day of the year 

message: "A precise date is specified by the ISO week-numbering year in the format YYYY, a week number in the format ww prefixed by the letter 'W', and the weekday number, a digit d from 1 through 7, beginning with Monday and ending with Sunday." WRONG. Technically, Sunday is 0, not 7. Because 1 week is already 7 days and Base 7 doesn't have the number 7. Also, in "The last week of the ISO week-numbering year, i.e. W52 or W53, is the week before W01 of the next year.", there is no W53 or WK53. The first week of the year is W00 or WK00. Please don't delete this text. Thank you for understanding. 2404:3C00:502F:4C80:94CC:986C:1979:3C38 (talk) 06:18, 3 March 2021 (UTC)
replies: text: This is nonsense that has nothing to do with the actual standard. — Christoph Päper 07:31, 12 April 2021 (UTC)
thread_title:  IMPORTANT 

message: It would be better to add 1 or 2 8-day weeks every year, so every year starts with Sunday. The weeks should be numbered from 00 to 51 and the days should be numbered from 0 to 6 or 7. That way, it would be easier to skip count.
SKIP COUNTING BY 10 DAYS USING WEEK DATE FORMAT
0000-01-3
0000-02-6
0000-04-2
0000-05-5
0000-07-1
0000-08-4
0000-10-0
0000-11-3
0000-12-6
0000-14-2
And so on...  2404:3C00:502F:4C80:E1F6:7353:D1D1:F484 (talk) 03:39, 24 July 2021 (UTC)
replies: text: You will probably find something like that on the Calendars Wikia, but not in this Wikipedia article which reports the design of the respective international standard. — Christoph Päper 11:44, 27 July 2021 (UTC)
thread_title:  Irregular week length 

message: I wonder what the reasoning was behind the change of contemporary examples to 1970s/80s dates instead of the more recent and arguably more relatable dates in the 2000s: https://en.wikipedia.org/w/index.php?title=ISO_week_date&type=revision&diff=1013225877&oldid=1012594781
Also the example about a bug with Twitter in 1986 does not make any sense at all now: "A programming bug confusing these two year numbers is probably the cause of some Android users of Twitter being unable to log in around midnight of 29 December 1986 UTC."
I propose reverting those changes.
Fdemmer (talk) 08:21, 23 March 2021 (UTC)
replies: text: I agree. The standard itself mostly uses examples from the 1980s, because that's when its predecessors were first published. — Christoph Päper 07:30, 12 April 2021 (UTC)
thread_title:  Recent change in "Examples of contemporary dates..."