Date representation

Introduction

A problem that has always existed, but is coming into general awareness is the method used to represent dates and time.

In the UK, we historically write dates in a form that looks like 12th. April 1998, or 12/04/98 - in other words we put the date in the order day - month - year.

However in the USA dates are historically written as month - day - year, or look like April 12th. 1998, or 04/12/98.

There is an existing problem, in that the date 05/07/97 can be the 5th. July 1997, or can be the 7th. May 1997.

And the reader has no way of knowing which it is.

The problem is compounded with application software packages that automatically insert dates into documents, headers and footers, or spreadsheet cells, as the reader does not know what representation is in use.

It is also common to have documents where both representations are used - the author uses one out of habit, and the computer being used inserts dates using the other representation.

In a few years time documents will be produced with dates such as 02/03/04 - what does that mean ?

Various bodies all over the world have recognised this problem, and have taken steps to standardise the way dates are represented, and to get this standard used all over the world.

There is now an international standard known as ISO 8601, which defines the way to represent dates.

In Europe, it is known as EN 8601.

Just to be different, in the UK it is known as BS EN 8601.

In the USA, it has become an ANSI standard.

So this method of representing dates has now been officially adopted by all these countries, plus many more.

ISO 8601 - dates

The essence of ISO 8601 is that dates are written in the form year - month - day.

The "correct" way to do it is to use numbers, such as 1998-08-02. This is the standard.

However a modified method is to insert the month in text form, ie, 1998-August-02, or 1998-Aug-02.

These two methods have been deemed as acceptable, even though they do not strictly comply with the ISO 8601 standard.

Note that the year is always first, and is always written with four digits.

The month always follows the year, and always uses two digits ( or text)

The day is always last, and always uses two digits.

The year, month, and day are always seperated by hyphens without spaces.

ISO - time

The standard ISO 8601 also defines the way that time should be represented.

The 24 hour clock is a must, the use of "am" and "pm" are not permitted.

Time is always written in the order hours : minutes : seconds, and are seperated by colons without spaces.

Two digits are always used for hours, minutes and seconds.

It is not neccessary to write in the seconds digits if they are not required.

Note that when writing times and dates, the date always comes first.

ISO 8601 - examples

An example therefore of a composite time and date written according to ISO 8601 :-

2.15 pm on the 3rd June 1998 would be written as

9 seconds after 2.15 pm on the 3rd June 1998 would be written as

Finally ....

It is strongly recommended that everybody, both as individuals and corporately through work, adopts the method of writing dates and times shown above.

Set up all computers to insert dates and / or time in this format.

It is the only way in which even more profound confusion as we go towards year 2000 can be avoided.

© 1999 Ron Turner

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