Explain How Windows Explorer uses DST for file datetime

  • Article

Q: Could you explain How Windows Explorer uses DST for file datetime?

A: Timestamps are values that specify a date and time combination. Applications that must handle timestamps typically store those timestamps in Universal Coordinated Time (UTC). The advantage of UTC is that UTC is universal and does not vary. UTC is not subject to local time zones or to DST.

 

However, UTC is neither user-friendly nor relevant to most users. Although UTC is the obvious choice for storage, it is not a good choice for display. Therefore, most applications convert UTC times to local time before they display the timestamp to the user. For example, Windows Explorer applies the time zone and DST setting to the UTC timestamp before it displays dates and times for files in a Windows NT File System (NTFS) directory.

 

You can find detailed information about DST at: support.microsoft.com/kb/932955, and more on timestamps at office.microsoft.com/en-us/help/HA102201961033.aspx and blogs.msdn.com/mthree/archive/2007/02/20/your-questions-how-does-windows-handle-historical-events-with-daylight-saving-time-updates.aspx.