Regional date formats vary throughout the world and it's often difficult to find a human-friendly date format that feels intuitive to everyone. The advantage of dates formatted like 2017-07-17 is that they follow the order of largest to smallest units: year, month, and day. This format also doesn't overlap in ambiguous ways with other date formats, unlike some regional formats that switch the position of month and day numbers. These reasons, and the fact this date format is an ISO standard, are why it is the recommended date format for changelog entries.

The first time the ratio of length to width was written in a letter dated 25 October 1786. This letter was from the German Georg Christoph Lichtenberg to Johann Beckmann. He wrote here about the advantages of basing paper on a √2 ratio. Lichtenberg is known for the ratio between length and width of a surface which remains the same after the narrated halving of the surface. The result is 1:√2.

ISO 8601 specifies the use of uppercase letter T to separate the date and time. PostgreSQL accepts that format on input, but on output it uses a space rather than T, as shown above. This is for readability and for consistency with RFC 3339 as well as some other database systems.

The URN “urn:iso:std:iso:19719:ed-1:v1:en,fr” denotes the first version of the first edition of ISO 19719, which is published bilingually in English and French.

The second edition was published in December 2018.

ISO 639-3 extends the ISO 639-2 alpha-3 codes with an aim to cover all known natural languages.

Through a linkpin called "Property Value Alias", Unicode has made a 1:1 connection between a script defined, and its ISO 15924 standard.

Language Range ... matches ... does not match de de, de-CH, de-AT, de-DE, de-1901, de-AT-1901 en, fr-CH

He proposed the standardized paper size system used globally today except in Canada and the US defined by ISO 216, which has A4 as the most commonly used size.

This document includes an Internet profile of the ISO 8601 [ISO8601] standard for representation of dates and times using the Gregorian calendar.

Do I have to use the yyyy-mm-dd date format? Yes. That date format is defined by ISO 8601. It is an internationally accepted way to represent dates. If you don't like typing the date that way, use the due date and threshold date pickers in the task text editor.