A summary of the international standard date and time notation

International Standard ISO 8601 specifies numeric representations of date and time. This standard notation helps to avoid confusion in international communication caused by the many different national notations and increases the portability of computer user interfaces. In addition, these formats have several important advantages for computer usage compared to other traditional date and time notations. The time notation described here is already the de-facto standard in almost all countries and the date notation is becoming increasingly popular.

Especially authors of Web pages and software engineers who design user interfaces, file formats, and communication protocols should be familiar with ISO 8601.

where YYYY is the year in the usual Gregorian calendar, MM is the month of the year between 01 (January) and 12 (December), and DD is the day of the month between 01 and 31.

Other commonly used notations are e.g. 2/4/95, 4/2/95, 95/2/4, 4.2.1995, 04-FEB-1995, 4-February-1995, and many more. Especially the first two examples are dangerous, because as both are used quite often in the U.S. and in Great Britain and both can not be distinguished, it is unclear whether 2/4/95 means 1995-04-02 or 1995-02-04. The date notation 2/4/5 has at least six reasonable interpretations (assuming that only the twentieth and twenty-first century are reasonable candidates in our life time).

Leave a Comment