Editing 1601 (section)

{{Year dab|1601|the work by Mark Twain|1601 (Mark Twain)}}
{{Year nav|1601}}
[[File:Siege and Battle of Kinsale, 1601.jpg|right|thumb|250px|December 24: [[Siege of Kinsale]] ended]]
{{C17 year in topic}}

{{Year article header|1601}} This [[Epoch (reference date)#Computing|epoch]] is the beginning of the 400-year Gregorian leap-year cycle within which digital files first existed; the last year of any such cycle is the only leap year whose year number is divisible by 100.

[[January 1]] of this year (1601-01-01) is used as the base of file dates<ref>[[Microsoft Windows]] [http://support.microsoft.com/kb/188768 technical note on file dates, referencing year 1601]</ref> and of Active Directory Logon dates<ref>[[Microsoft Windows]] [http://www.microsoft.com/technet/scriptcenter/topics/win2003/lastlogon.mspx technical note on file dates, referencing year 1601] {{Webarchive|url=https://web.archive.org/web/20090308124119/http://www.microsoft.com/technet/scriptcenter/topics/win2003/lastlogon.mspx |date=March 8, 2009 }}</ref> by [[Microsoft Windows]]. It is also the date from which ANSI dates are counted and were adopted by the American National Standards Institute for use with COBOL and other computer languages. All versions of the Microsoft Windows operating system from Windows 95 onward count units of one hundred nanoseconds from this epoch as a counter having 63 bits until 30828/9/14 02:48:05.4775807.<ref>{{cite web|url=http://www.decimaltime.hynes.net/dates.html|title=Decimal Time.net}}</ref> [[April 1]] of this year is the earliest possible calendar date in [[Microsoft Outlook]].<ref>{{Cite web |last=Office-Watch.com |date=2019-07-23 |title=What's the earliest date possible in Outlook? |url=https://office-watch.com/2019/whats-the-earliest-date-possible-in-outlook-and-workaround/ |access-date=2024-03-13 |website=Office Watch |language=en-US}}</ref>