The ISO 8601 standard establishes an internationally recognized format for presenting data: the form hours-minutes-seconds or, for dates, the form year-month-day . This structure allows you to place the figures directly one after the other, but you can also use hyphens to separate them, if you want to facilitate their reading. Thus, in the basic format of ISO 8601, the date September 7, 2019 would have the form 20190907 or, in its hyphenated version, 2019-09-07 . Expressions for hours are divided into hours, minutes and seconds, so in ISO 8601 they have the form 12:07:22 . With these ISO date formats (also called ISO date formats), country-specific conventions become dispensable, at least in electronic media . The different expressions are thus unified and cause less confusion.
Another designation for the ISO 8601 standard is EN 28601 (in its form for EU standards). This format not only serves to indicate points in time , but also periods : for this, the starting time or date is marked with the letter P to separate it from the next time data. Therefore, a period starting on September 6, 2019 at 8:00 p.m. and lasts a month, 5 days, and 3 hours, for example, would have the form 2019-09-06T20P1M5D3H in the unified ISO format..
All data, such as times, dates or periods, follows a specific order in the ISO standard: from the largest to the smallest unit, that is, in descending order . Thus, following the natural scale of the value of each unit, a larger unit will always appear before a smaller one. The advantage of this system is that it leads to the same result whether the data is classified according to lexicographic criteria, as if it is done chronologically.