{"id":18913,"date":"2009-03-06T10:00:00","date_gmt":"2009-03-06T10:00:00","guid":{"rendered":"https:\/\/blogs.msdn.microsoft.com\/oldnewthing\/2009\/03\/06\/why-is-the-win32-epoch-january-1-1601\/"},"modified":"2009-03-06T10:00:00","modified_gmt":"2009-03-06T10:00:00","slug":"why-is-the-win32-epoch-january-1-1601","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/oldnewthing\/20090306-00\/?p=18913","title":{"rendered":"Why is the Win32 epoch January 1, 1601?"},"content":{"rendered":"<p>Public Service Announcement: This weekend marks the start of Daylight Saving Time in most parts of the United States.<\/p>\n<p> The <code>FILETIME<\/code> structure records time in the form of 100-nanosecond intervals since January 1, 1601. Why was that date chosen? <\/p>\n<p> The Gregorian calendar operates on a 400-year cycle, and 1601 is the first year of the cycle that was active at the time Windows&nbsp;NT was being designed. In other words, it was chosen to make the math come out nicely. <\/p>\n<p> I actually have the email from Dave Cutler confirming this. <\/p>\n","protected":false},"excerpt":{"rendered":"<p>Public Service Announcement: This weekend marks the start of Daylight Saving Time in most parts of the United States. The FILETIME structure records time in the form of 100-nanosecond intervals since January 1, 1601. Why was that date chosen? The Gregorian calendar operates on a 400-year cycle, and 1601 is the first year of the [&hellip;]<\/p>\n","protected":false},"author":1069,"featured_media":111744,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[26,108],"class_list":["post-18913","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-oldnewthing","tag-other","tag-time"],"acf":[],"blog_post_summary":"<p>Public Service Announcement: This weekend marks the start of Daylight Saving Time in most parts of the United States. The FILETIME structure records time in the form of 100-nanosecond intervals since January 1, 1601. Why was that date chosen? The Gregorian calendar operates on a 400-year cycle, and 1601 is the first year of the [&hellip;]<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/18913","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/users\/1069"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/comments?post=18913"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/18913\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media\/111744"}],"wp:attachment":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media?parent=18913"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/categories?post=18913"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/tags?post=18913"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}