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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.
Possible ISO week numbers are in the range 01 to 53. (There is one historic exception: the year in which the Gregorian calendar was introduced had less than 365 days and less than 52 weeks.) Proof: Per definition, the first week of a year is W01 and consequently days before week W01 belong to the previous year and so there is no week with lower numbers.
Considering the highest possible week number, the worst case is a leap year like 1976 that starts with a Thursday, because this keeps the highest possible number of days of W01 in the previous year, i.e. In this case, the Sunday of W52 of the worst case year is day number 4 51*7=361 and 361-366=5 days of W53 belong still to this year, which guarantees that in the worst case year day 4 (Thursday) of W53 is not yet in the next year, so a week number 53 is possible.
In this case, the Sunday of week 52 would be day number 3 52*7=367, i.e.
only the last 367-365=2 days of the W52 reach into the next year and consequently, even a worst case year like 1999 has a week W52 including the days 1999-12-27 to 2000-01-02. Both day and year are useful units of structuring time, because the position of the sun on the sky, which influences our lives, is described by them.
An abbreviated version of the year and week number like is sometimes useful as a compact code printed on a product that indicates when it has been manufactured.
Apart from the recommended primary standard notation YYYY-MM-DD, ISO 8601 also specifies a number of alternative formats for use in applications with special requirements.Note: The value 60 for ss might sometimes be needed during an inserted leap second in an atomic time scale like Coordinated Universal Time (UTC).A single leap second is inserted into the UTC time scale every few years as announced by the International Earth Rotation Service in Paris, to keep UTC from wandering away more than 0.9 s from the less constant astronomical time scale UT1, which is defined by the actual rotation of the earth.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.