Why aren’t more marketers using ISO 8601, the international standard for date and time formats ^[1]?

Everyone with a marketing role has a need to eliminate ambiguity from their communication, and this is such a simple thing to fix that I am always surprised to see highly localized and ambiguous formats for dates used in materials being designed for international and multi-cultural audiences.

For example, 01/03/09 represents a date. However, 01/03/09 is ambiguous. Which of the following legitimate interpretations does it mean?

• 9th of March 2001
• 3rd of September 2001
• 1st of March 2009

Fixing the year, by making it 4 digits long helps a bit, but is still ambiguous:

• 01/03/2009 (January or March?)

You may try to improve the situation by spelling out the date as in the three examples above, but they are also local formats that won’t mean much in non-English speaking countries.

What’s more if you want to use dates like this elsewhere, in filenames on a computer  for example – the computer will be unable to return any meaningful sorting for those files based on the filename, as either the day of month or the month will be the main sort key.

ISO 8601 prescribes a simple date format: 2009-03-01 with the year first, which can be easily and unambiguously understood around the world.

A huge added advantage of this format is when collating or sorting materials – computers interpret that date properly, even when it isn’t recognized as a date.

For example, the following filenames which include ISO dates will sort properly just about anywhere:

• Marketing Plan 2008-02-02 – final.doc
• Marketing Plan 2009-01-20 – draft.doc
• Marketing Plan 2009-01-24 – draft.doc
• Marketing Plan 2009-02-05 – final.doc

Not one of the other popular formats would produce a useful ordering from such a sort.

It is probably one of the easiest things you can do to remove ambiguity in your communication around the world.

Further reading:

Wikipedia has a very approachable entry for ISO8601 ^[1], and you can find out more about the benefits of using ISO8601 on the web ^[2] at the W3C.

• ISO 8601:2004 – Data elements and interchange formats — Information interchange — Representation of dates and times ^[3]