https://community.esri.com/t5/arcgis-pro-questions/datetime-functions/m-p/1022410#M36732 <P>its a file geodatabase, python does have a min of year 1 AD, I have got the slider to work, by using 1 day = 1 year with year on being 31/12/1899&nbsp;&nbsp;</P> Tue, 02 Feb 2021 01:24:34 GMT PaulPrevedoros1 2021-02-02T01:24:34Z https://community.esri.com/t5/arcgis-pro-questions/datetime-functions/m-p/1022384#M36730 <P>I am trying to systematically display BCE data and I have discovered something strange. When perform a calculate field on a date field and enter a value of -500000 the result is 16/01/531. Zero is 30/12/1899</P><P>I didn't think that the time suite worked this way?&nbsp;</P> Tue, 02 Feb 2021 00:15:46 GMT https://community.esri.com/t5/arcgis-pro-questions/datetime-functions/m-p/1022384#M36730 PaulPrevedoros1 2021-02-02T00:15:46Z https://community.esri.com/t5/arcgis-pro-questions/datetime-functions/m-p/1022407#M36731 <P>The story behind 30-Dec-1899 as the "Zero Date" is a long one, but pretty well summarized <A href="https://stackoverflow.com/questions/3963617/why-is-1899-12-30-the-zero-date-in-access-sql-server-instead-of-12-31" target="_self">here at Stack Overflow</A>.</P><P>How is your data being stored? Other databases and programs have similarly long-established and sometimes-interesting stories behind their "Zero Date", like IBM SPSS's <A href="https://www.wdl.org/en/item/2837/" target="_self">October 14, 1582</A>, which never actually existed.</P> Tue, 02 Feb 2021 01:12:08 GMT https://community.esri.com/t5/arcgis-pro-questions/datetime-functions/m-p/1022407#M36731 jcarlson 2021-02-02T01:12:08Z https://community.esri.com/t5/arcgis-pro-questions/datetime-functions/m-p/1022410#M36732 <P>its a file geodatabase, python does have a min of year 1 AD, I have got the slider to work, by using 1 day = 1 year with year on being 31/12/1899&nbsp;&nbsp;</P> Tue, 02 Feb 2021 01:24:34 GMT https://community.esri.com/t5/arcgis-pro-questions/datetime-functions/m-p/1022410#M36732 PaulPrevedoros1 2021-02-02T01:24:34Z