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charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: qt.io X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: DU0PR02MB8218.eurprd02.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 1a88dfa2-3336-403f-861e-08dabc0d9b5f X-MS-Exchange-CrossTenant-originalarrivaltime: 01 Nov 2022 13:33:05.3515 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 20d0b167-794d-448a-9d01-aaeccc1124ac X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: 0Y8+9byv597snIn49L+FfAWN2UcJkg38VzqUmHFJeKsF453mPAgiFsmzY6Z5qlAgivHIDMlF43k0XKNVdPhszQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DB9PR02MB8347 Archived-At: Subject: Re: [Sedate] [Ntp] [art] [TICTOC] [Cbor] Two specifications on timestamps nearing WGLC X-BeenThere: sedate@ietf.org X-Mailman-Version: 2.1.39 Precedence: list List-Id: Serialising Extended Data About Times and Events List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 01 Nov 2022 13:33:14 -0000 Doug Arnold (1 November 2022 14:06) wrote:=0A= > I agree with Danny. The proper way to handle time zones is at the=0A= > presentation layer of an application that displays local time for=0A= > humans. Machines should never use local time for any other purpose.=0A= =0A= I wish I could agree with you; all times are UTC inside the code, only=0A= at the point of presentation do politicians' decisions mess with how=0A= it's described.=0A= =0A= However, when the user is booking an event several months in advance,=0A= they want to say "that day, that time on that day, in the local=0A= time-zone of that place" and, if the politicians change that zone's=0A= offset from UTC, or DST habits, in the mean time, the calendars that=0A= hold records of that event should all preserve the time and date in that=0A= zone, not the UTC time, of the event. So they have to store the event's=0A= timing relative to a specified zone. Consequently, therefore, the data=0A= exchange formats by which calendars tell each other (via content=0A= inserted in e-mails, as often as not) those details need to be expressed=0A= in terms that document the zone and how the time is understood in that=0A= zone. There are lots of other situations where software *must* likewise=0A= handle zoned date-times.=0A= =0A= Then there is the fuzzy zone of what counts as displaying it to humans.=0A= When a web-server lots an error, it's going to convert the time into a=0A= human-readable form to include as a timestamp in the log file. The=0A= human who is going to read it may well find it more intelligible if the=0A= formatting used is their local time, or the standard zone of the=0A= organization whose server it is, even though that has some weird=0A= behaviour at two points in the year, one of which skips an hour, the=0A= other of which repeats it (with a different offset suffix or zone=0A= abbreviation). Until the human looks at the log file, it's not being=0A= displayed, but still it goes into the log file in human-readable form.=0A= =0A= Having said all of which, I do totally agree with Danny - please keep=0A= anything at all to do with time-zones as far away from NTP as possible,=0A= =0A= Eddy.=0A=