Editing List of non-standard dates (section)

==Software==
===January 0===
[[Microsoft Excel]] displays the day before January 1, 1900 (the earliest date it can represent) as January 0, 1900.<ref name="m">{{cite web |url=http://www.techrepublic.com/article/how-do-i-perform-basic-formatting-in-excel-2003/ |work=[[TechRepublic]] |title=How do I... Perform basic formatting in Excel 2003? |first=Scott |last=Lowe |date=May 11, 2007}}</ref> It also treats 1900 incorrectly as a leap year (whereas only centuries divisible by 400 are), so it displays the day before March 1, 1900, as the non-existent February 29 instead of [[February 28]]. This means March 1, 1900 is the earliest date that can be used reliably in Excel.

===February 31===
February 31, 32, and 33 were used to calculate weather data by making each month the same length.<ref>{{cite journal |last1=Everett |first1=J. D. |title=Description of a method of reducing observations of temperature |journal=American Journal of Science |date=1 January 1863 |volume=s2-35 |issue=103 |pages=17–31 |doi=10.2475/ajs.s2-35.103.17 |bibcode=1863AmJS...35...17E |s2cid=130637323 |url=https://zenodo.org/record/1621032 }}</ref>

===Other non-standard dates===
Other non-standard dates are sometimes used in [[Application software|software engineering]]. For example, [[Java (programming language)|Java]] (specifically the java.util.Calendar class) allows dates such as February 0 (= January 31) and April 31 (= May 1).