ISO 8601
ISO 8601
Public Service Announcement:
Our different ways of writing dates as numbers can lead to online confusion. That's why in 1988 ISO set a global standard numeric date format. This is the correct way to write numeric dates:
2013-02-27
The following formats are therefore discouraged: 02/27/2013 02/27/13 27/02/2013 27/02/13 20130227 2013.02.27 27.02.13 27-02-13 27.2.13 2013. II. 27. 27 ⁄ 2 -13 2013.158904109 MMXIII-II-XXVII MMXIII LVII ⁄ CCCLXV 1330300800 ((3+3)×(111+1)-1)×3/3-1/3 3 2 27 2013 [the numbers 2013, 02, and 27 written overlapping each other] 10/11011/1101 02/27/20/13 2 0 5 3 1 1 2 67 4 37 8 [A black cat with 2-27-13 scrawled across its body in dripping white paint.] Cat: Hissss

When abbreviating the date into numerical form, various areas of the world tend to list the year, month, and day in different orders (as well as with different delimiting symbols), which can cause confusion particularly when the day value is 12 or lower allowing it to be easily interpreted as the month and vice versa. As a public service announcement , this comic states that there is in fact one international standard for writing numeric dates, set by the International Organization for Standardization in its ISO 8601 standard: YYYY-MM-DD.
The comic then proceeds to list several discouraged ways of writing out the date of the comic's publication, as they do not match the standard. It begins with several commonly used ones in countries around the world, but then begins to list increasingly uncommon ways, ranging from strange (Roman numerals) to quirky (binary, Unix time) to essentially impossible (painting the numbers onto a black cat).
The title text provides a perfect example of the kind of ambiguity that can arise when non-standard formats are used. The ISO standard was in fact published on 1988-06-05 and amended on 2004-12-01. This is mentioned in the title text in MM/DD/YY format; however, there is no way to naturally figure this out, particularly with the second date.
With the year truncated to two digits and all three numbers at 12 or lower, the date referring to December 1, 2004 (the digits pairs 12, 01 and 04) has a number of misinterpretations. Usually 12 th Jan '04 (if written as US-style but read as European, or vice-versa) but with ISO-influenced "YY MM DD" ordering as one side or other of the misunderstanding it can easily become the 12 th day of April 2001, the 4 th day of December 2001 and the 4 th of January 2012. It takes two such communication errors to 'become' the 1 st day of April 2012.
Date formats were again the subject in 1340: Unique Date and 2562: Formatting Meeting .
The other mentioned formats are:
Public Service Announcement:
Our different ways of writing dates as numbers can lead to online confusion. That's why in 1988 ISO set a global standard numeric date format. This is the correct way to write numeric dates:
2013-02-27
The following formats are therefore discouraged: 02/27/2013 02/27/13 27/02/2013 27/02/13 20130227 2013.02.27 27.02.13 27-02-13 27.2.13 2013. II. 27. 27 ⁄ 2 -13 2013.158904109 MMXIII-II-XXVII MMXIII LVII ⁄ CCCLXV 1330300800 ((3+3)×(111+1)-1)×3/3-1/3 3 2 27 2013 [the numbers 2013, 02, and 27 written overlapping each other] 10/11011/1101 02/27/20/13 2 0 5 3 1 1 2 67 4 37 8 [A black cat with 2-27-13 scrawled across its body in dripping white paint.] Cat: Hissss
