International Date Format (ISO 8601) and Time Measurements

#date_formats #iso_8601 #yyyymmdd

The YYYY MM DD date format is the internationally agreed concise format for unambiguous dates and ought to be adopted by everyone. It is logical, with the biggest denominators being listed first (the same way as numbers, times and weights are), making it easily sortable and utterly clear. The International Organization for Standardization specification for the International Date Format is the ISO-8601 format, adopted so far by the computer industry in general (due to the advantages of sorting by dates in filenames), United Nations, commerce groups, scientific communities and some Western governments, although most individuals generally continue to use culture-specific date formats. "2005 03 29" is an example of an ISO-8601-compliant date.

1. International Date Format (ISO 8601): Year, Month, Day

1.1. YYYY MM DD - Today's Date is: 2005 08 16

#germany #UK #USA

The International Organization for Standardization (ISO) standard ISO-8601 (2004) specifies the international date and time convention, replacing earlier ISO-8601 standards. Local date formats such as "01/02/03" are ambiguous and inaccurate, and could mean "January 2, 2003" in the USA or "1 February 2003" in other places. The full standard runs to a heady length of 33 pages.

How can one avoid confusion when a date like 08/04/02 has at least six different interpretations around the world? A notation like 01/02/03 could mean 1 February 2003 or 2 January 2003 or 2 March 2001. [...]

Wouldn't it be wonderful if there were an internationally agreed standard? Well, there is. It is ISO 8601, Data elements and interchange formats - Information interchange - Representation of dates and times.

ISO 8601 corresponds to the UN Working Party on the Facilitation of International Trade Procedures in its Recommendation 7.

ISO Article on International Date Format

Some advantages of adopting the International Date Format:

Across Europe the European Norm (EN) standard 28601 incorporates ISO-8601. "All members of CEN (all of Western Europe and Scandinavia, and most of Eastern Europe) are required to adopt the EN 28601 European Standard. Most have now done so" [Galpin 1998].

1.2. YYYY MMM DD - Today's Date is 2005 Aug 16

I have been using the YYYY MMM DD format since late 1999 when the Millennium Bug started to hit the news; I came up with the format independently of the International Organization for Standardization after thinking on what would make a good, universal, systematic date format that would be completely non-ambiguous. The difference (notice the third M in the middle), is that I use a 3-character English shorthand for the month, for example 2001 Jan 01. This makes it, in my mind, utterly clear what format I am (nearly) using. Once the world is largely familiar with it, the English month can be dropped and replaced with a more sensible number. Until then, it aids the transition. A major disadvantage of this halfway format is that it is not easily sortable; the English letters when used as filenames, for example, would result in "2002 Aug 10" appearing before "2002 May 10", which is unfortunate. When it is for human reading-eyes then I use YYYY MMM DD, when solely for data entry and filenames, YYYYMMDD is the only way to go and hence why ISO 8601 is most highly adopted by the computer industry.

2. The Babylonians Versus the French Revolution1

#christianity #judaism

We all know we divide time into 60 seconds, 60 minutes, 24 hours, 7 days, 4 weeks and 12 months. But in antiquity there have been many ways of recording the passage of time, and many ways to divide up the year into seasons and months. Although the Egyptians may have first divided the day into 24 hours over 5500 years ago2, it was the Babylonians in their star-gazing, moon-charting enthusiasm who divided time into divisions based on the movements of the moon and sun. They divided weeks into 7 days to correspond to phases of the moon, and hours and minutes into divisions of 60 because they had a base-60 numbering system3, and gave us the Zodiac.4. Moon-based and sun-based system became the foundation of Jewish and Christian calendars, and has remained in place as the world's most common system of time-telling. In Qur'an 9:36 it even says that God itself, not us humans, ordained the division of the year into 12 months.

The Babylonians were not ideological in their approach and their astronomers spent lifetimes making careful measurements of the stars and stellar bodies. Aristotle was amazed when he attained 1,903 years' worth of astronomical observations from Babylon, and Ptolemy, the Egyptian scientist, had a Babylonian record of eclipses that dated back to 747BCE. They "fixed the length of a tropical year within twenty-five seconds of the truth; their estimate of the sidereal year was barely two minutes in excess. They had detected the precession of the equinoxes. They knew the causes of eclipses, and, by the aid of their cycle called Saros, could predict them. Their estimate of the value of that cycle, which is more than 6,585 days, was within nineteen and a half minutes of the truth". They measured exactly how the moon covered up stars, and, correctly knew how the solar system was arranged and the order of the planets.5.

Unfortunately, most of this knowledge was wiped out by an ascendant Christianity which enforced its idea of the Earth as the centre of creation, and disregarded and oppressed astronomical sciences, burning books and imprisoning and torturing those who disagreed with the Churches simplistic notion of the planets6.

Base-60 calculations are far from practical and introduce many complications7. Calculating the number of days inbetween two dates is a horrendously multifaceted affair. We have moved on. Numbering systems are base-10 almost everywhere. Our recording of time should also change; such a change would have advantages in man-management, physics, programming, engineering, etc, where we'd no longer need to mix numbers from base-60 and base-10 numbering systems.

A system of base-10 temporal measurements was introduced during the French Revolution with 10 hours in a day, and 10 days in a week, but it was abandoned in the face of almost universal terror at the thought of changing our cherished (but odd) system of dividing time7.

Also see:

3. Use BCE and CE, not BC and AD


Wikipedia notes how the standard transition from BCE to CE is made according to ISO-8601 international standards.

CE means Common Era8 and is the name of the most popular dating system. The current year is 2000ce.

BCE means Before Current Era8 and it counts the time before CE, counting backwards. 1BCE is the year before 1CE.

There are also two older and deprecated dating letters:

BC means Before Christ8 and is a reference to a prediction of the Christian messiah's birth date made in the second millennium. The date of Jesus Christ's birth is known to be about 4 BCE, so the reference is poor.

AD means Anno domini which means "in the year of our lord"8.

CE has the same value as AD, and BCE has the same value as BC. They are interchangeable systems. CE and BCE are the correct terms to use for reasons of fairness. Less than a third of the world is Christian, and expecting others to conform to a religious convention that is not their own is immoral - the neutral system of CE and BCE is far fairer8. Using the term "BC" and "AD" shows inconsideracy for others' feelings and beliefs (unless of course they do not know the difference (like most people), which is why I wrote this!). Choosing to use "BCE" and "CE" is to avoid endorsing any religion, and is therefore suitable for communication in the modern world.

We have received many Emails about the use of CE and BCE:

  • Some Christians are distressed at the new terms. Some feel that AD and BC have been in use for centuries and that this tradition should be respected. Others see the switch to CE and BCE as just one more example of non-Christian religions being given precedence over Christianity.

  • Some Emailers, Christians and others, support the new terms. They feel bound by the Golden Rule -- to do onto others what they would wish be done to themselves. If AD and BC cause distress to others, then the Ethic of Reciprocity (of which the Golden Rule is one of many examples) would suggest that the terms be scrapped in favor of more neutral terms.

The fundamentalist Christians who think that because it is nicer to use religion-neutral terms, that "other religions are being put above Christianity" are incorrect: to use a neutral term is not to put any religion first, which is of course the most tolerant and respectful way to proceed in a multicultural world.

By Vexen Crabtree 2005 Aug 16
(Last Modified: 2014 Aug 29)
Parent page: Misc Pages

References: (What's this?)

Book Cover

The Koran. Penguin Classics edition. Originally published 1956. Current version published by Penguin Group Ltd, London, UK. Translation by N. J. Dawood. Quotes taken from 1999 edition.

Barnes-Svarney, Patricia
(1995, Ed.) New York Public Library Science Desk Reference. Paperback book. Published by The Stonesong Press Inc. and The New York Public Library, New York, USA.

Breuilly, O'Brien & Palmer
(1997) Religions of the World. Hardback book. Subtitled: "The Illustrated Guide to Origins, Beliefs, Traditions, & Festivals". Published by Lionheart Books. By Elizabeth Breuilly, Joanne O'Brien & Martin Palmer. Published for Transedition Limited and Fernleigh Books.

Crabtree, Vexen
(2009) "General Neophobia in Everyday Life: Humankind's Fear of Progress and Change" (2009). Accessed 2017 Feb 17.

Draper, John William. (1811-1882)
(1881) History of the Conflict Between Religion and Science. E-book. 8th (Amazon Kindle digital edition) edition. Published by D. Appleston and Co, New York, USA.

Fara, Patricia
(2009) Science: A Four Thousand Year History. Hardback book. Published by Oxford University Press. Fara has a PhD in History of Science from London University.

Mackenzie, Donald A.
(1915) Myths of Babylonia and Assyria. E-book. Amazon Kindle digital edition produced by Sami Sieranoja, Tapio Riikonen and PG Distributed Proofreaders.


  1. Added to this page on 2009 Nov 23.^
  2. Barnes-Svarney (1995) p71-73.^
  3. Fara (2009) p7,13-4.^
  4. Mackenzie (1915) Digital location 12-14. Added to this page on 2013 Apr 06.^
  5. Draper (1881) p13. Added to this page on 2012 Jun 11.^
  6. Christianity v. Astronomy: The Earth Orbits the Sun!^
  7. Fara (2009) p7, 13-4.^
  8. Breuilly, O'Brien & Palmer (1997) p6.^

© 2017 Vexen Crabtree. All rights reserved.