British dating system
by Markus Kuhn 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.
All of these alternatives can easily and automatically be distinguished from each other: The hyphens can be omitted if compactness of the representation is more important than human readability, for example as in In commercial and industrial applications (delivery times, production plans, etc.), especially in Europe, it is often required to refer to a week of a year.
Week 01 of a year is per definition the first week that has the Thursday in this year, which is equivalent to the week that contains the fourth day of January.
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. 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 standard notation for this variant representing the day 1995-02-04 (that is day 035 of the year 1995) is Leap years are years with an additional day YYYY-02-29, where the year number is a multiple of four with the following exception: If a year is a multiple of 100, then it is only a leap year if it is also a multiple of 400.
On the other hand, considering the lowest number of the last week of a year, the worst case is a non-leap year like 1999 that starts with a Friday, which ensures that the first three days of the year belong to the last week of the previous year.However the 12 months of a year are of some obscure mystic origin and have no real purpose today except that people are used to having them (they do not even describe the current position of the moon).In some applications, a date notation is preferred that uses only the year and the day of the year between 001 and 365 (366 in leap years).It is not intended as a replacement for language-dependent worded date notations such as “24.Dezember 2001” (German) or “February 4, 1995” (US English).