From: Tim Cross <theophilusx@gmail.com>
To: Max Nikulin <manikulin@gmail.com>
Cc: emacs-orgmode@gnu.org
Subject: Re: [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda
Date: Sun, 15 Jan 2023 18:53:26 +1100 [thread overview]
Message-ID: <63c3b1a4.a70a0220.225b1.83fe@mx.google.com> (raw)
In-Reply-To: <tpvtod$2qd$1@ciao.gmane.io>
Max Nikulin <manikulin@gmail.com> writes:
> On 15/01/2023 03:30, Tim Cross wrote:
>> The UTC time stays the same, but the
>> meeting time for me changes twice per year (moving forward/backward an
>> hour).
>
> Meeting time remains the same expressed as local time (15:00), but alternates between
> 04:00 and 05:00 UTC. So repeating schedule can not be stored as UTC, instead UTC timestamp
> should be calculated from local time for each date. (Even libc can do it while you work
> with single timezone.) It is OK to store in UTC already passed events, but local time
> still may be more compact and user friendly.
>
> Actually I am trying to draw attention to a more tricky case when timestamp stored as
> local time is even more important. Event time is bound to local time, and timezone
> database changed due to new rules for this time zone: the government decided to cancel or
> introduce DST transitions or to extend/shorten interval when daylight saving time is
> active. For a timezone without DST time offset may be changed as well.
>
> While timezone database is stable, you can calculate UTC timestamps for any moments
> expressed in local time. When new rules are published some future UTC timestamps become
> invalid. If you know local time, you may update UTC timestamps. If you store just UTC
> timestamp you have a trouble.
>
> Paul Eggert provided an example of updating time transition history, so what is
> authoritative: local time or UTC, applies to the past as well. However I do not agree with
> Paul completely. It is necessary to decide for each timestamp, what is the primary data,
> time offset (so timezone identifier should be updated) or local time (so time offset
> should be updated keeping timezone identifier).
>
> https://debbugs.gnu.org/cgi/bugreport.cgi?bug=54764#30
> Re: bug#54764: encode-time: make DST and TIMEZONE fields of the list
> Thu, 14 Apr 2022 15:46:58 -0700
>> Again, that depends on the application. It's typically wrong to store an old timestamp
>> in a form like "1950-07-01 00:00 Europe/Lisbon", because there is no standard for what
>> "Europe/Lisbon" means. If you update your copy of TZDB, or interpret such a timestamp on
>> another computer, that can change the interpretation of such a timestamp. In this
>> particular case, a change in TZDB release 2021b altered the interpretation of this old
>> timestamp because we discovered that DST was observed in 1950 in Portugal.
>> If you want to keep the TZDB identifier for advice about how to interpret dates relative
>> to a timestamp, that's fine. But you should keep the UT offset in addition to the TZDB
>> identifier, if you want your app to be fully accurate and useful. For example, you
>> should store "1950-07-01 00:00:00 +0000 Europe/Lisbon" for a timestamp generated by TZDB
>> release 2021a, so that when you interpret the timestamp in release 2021b you'll have an
>> idea of what you're dealing with.
>
> So keeping redundant information may be crucial to get warnings that some timestamps need
> to be reviewed.
WRT future timestamps, we would probably have to take the same approach
as postgres i.e. the timezone rules in force at the time the timestamp
is created are assumed to be 'forever'. While this is not true, it is
really the only solution you can adopt and you just have ot accept that
there is the chance that the rule will change in the future and the
timestamp will then be incorrect.
next prev parent reply other threads:[~2023-01-15 7:57 UTC|newest]
Thread overview: 330+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-13 8:56 [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda Daryl Manning
2023-01-13 12:51 ` Tim Cross
2023-01-14 6:27 ` Daryl Manning
2023-01-14 12:46 ` Jean Louis
2023-01-14 11:18 ` Ihor Radchenko
2023-01-14 11:26 ` Daryl Manning
2023-01-14 11:42 ` Ihor Radchenko
2023-01-15 5:11 ` Max Nikulin
2023-01-15 13:41 ` Ihor Radchenko
2023-01-16 16:43 ` Max Nikulin
2023-01-16 18:37 ` Ihor Radchenko
2023-01-17 17:40 ` Max Nikulin
2023-01-18 9:59 ` Ihor Radchenko
2023-01-18 16:25 ` Jean Louis
2023-01-18 16:24 ` [SOLUTION] " Jean Louis
2023-01-20 10:57 ` Ihor Radchenko
2023-01-20 11:29 ` Daryl Manning
2023-01-20 11:36 ` Ihor Radchenko
2023-01-20 15:10 ` Daryl Manning
2023-01-20 11:39 ` Fraga, Eric
2023-01-20 11:48 ` Ihor Radchenko
2023-01-21 12:55 ` Jean Louis
2023-01-21 13:41 ` Ihor Radchenko
2023-01-21 9:21 ` Ihor Radchenko
2023-01-21 10:14 ` Max Nikulin
2023-01-22 11:49 ` Ihor Radchenko
2023-01-20 22:51 ` Tim Cross
2023-01-14 13:03 ` Tim Cross
2023-01-14 13:22 ` Ihor Radchenko
2023-01-15 19:10 ` Jean Louis
2023-01-16 11:21 ` Ihor Radchenko
2023-01-16 11:30 ` Daryl Manning
2023-01-16 11:39 ` Ihor Radchenko
2023-01-16 15:43 ` Daryl Manning
2023-01-16 19:07 ` Ihor Radchenko
2023-01-16 19:22 ` Robert Horn
2023-01-16 19:41 ` Ihor Radchenko
2023-01-16 20:47 ` Robert Horn
2023-01-16 21:02 ` Tom Gillespie
2023-01-16 21:48 ` Robert Horn
2023-01-17 8:53 ` Ihor Radchenko
2023-01-17 3:55 ` Daryl Manning
2023-01-17 8:22 ` Tim Cross
2023-01-17 9:15 ` Ihor Radchenko
2023-01-17 9:45 ` Tim Cross
2023-01-18 9:15 ` Ihor Radchenko
2023-01-18 11:43 ` Tim Cross
2023-01-18 12:02 ` Ihor Radchenko
2023-01-18 21:16 ` Tim Cross
2023-01-19 5:29 ` Jean Louis
2023-01-19 6:25 ` Thomas S. Dye
2023-01-19 14:17 ` Jean Louis
2023-01-19 15:55 ` Thomas S. Dye
2023-01-21 13:10 ` Jean Louis
2023-01-21 16:23 ` Thomas S. Dye
2023-01-21 13:50 ` Jean Louis
2023-01-21 14:31 ` Max Nikulin
2023-01-21 16:55 ` Thomas S. Dye
2023-01-19 7:23 ` Tim Cross
2023-01-19 14:32 ` Jean Louis
2023-01-19 20:09 ` Tim Cross
2023-01-19 23:02 ` Thomas S. Dye
2023-01-19 23:51 ` Tim Cross
2023-01-20 0:24 ` Thomas S. Dye
2023-01-20 3:46 ` Tim Cross
2023-01-20 6:14 ` Thomas S. Dye
2023-01-27 6:06 ` Sterling Hooten
2023-01-27 6:09 ` Daryl Manning
2023-01-27 9:54 ` Jean Louis
2023-01-27 21:04 ` Tim Cross
2023-01-29 4:09 ` Jean Louis
2023-01-29 6:21 ` Thomas S. Dye
2023-01-29 6:46 ` Daryl Manning
2023-01-29 14:10 ` Ihor Radchenko
2023-01-30 19:37 ` Jean Louis
2023-01-31 0:53 ` Thomas S. Dye
[not found] ` <0597910b-9b01-3c0c-5d06-da171e0de4cd@gmx.at>
2023-01-31 6:08 ` Jean Louis
2023-01-29 6:31 ` Max Nikulin
2023-01-30 20:36 ` Jean Louis
2023-01-30 20:38 ` Jean Louis
2023-01-29 20:26 ` Tim Cross
2023-01-30 20:55 ` Jean Louis
2023-01-30 21:54 ` Tim Cross
2023-01-31 7:04 ` Jean Louis
2023-01-31 8:14 ` Max Nikulin
2023-01-31 13:02 ` Jean Louis
2023-01-27 11:09 ` Ihor Radchenko
2023-01-27 12:49 ` Sterling Hooten
2023-01-27 13:00 ` Ihor Radchenko
2023-01-27 15:03 ` Jean Louis
2023-01-30 13:08 ` Ihor Radchenko
2023-01-27 20:58 ` Tim Cross
2023-01-30 11:25 ` Greg Minshall
2023-01-31 11:48 ` [POLL] Proposed syntax for timestamps with time zone info (was: [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda) Ihor Radchenko
2023-01-31 12:19 ` Daryl Manning
2023-01-31 12:41 ` Ihor Radchenko
[not found] ` <CAL9aZksf8AGF=dXg0KAtLPyu1ATt1fLpvdsjN6GMCuK2KRQ56w@mail.gmail.com>
2023-01-31 13:33 ` Ihor Radchenko
2023-01-31 13:22 ` Jean Louis
2023-01-31 13:46 ` Ihor Radchenko
2023-01-31 19:59 ` Jean Louis
2023-02-01 12:42 ` Ihor Radchenko
2023-02-01 15:28 ` Jean Louis
2023-02-01 16:30 ` Ihor Radchenko
2023-01-31 20:12 ` Jean Louis
2023-02-01 5:46 ` tomas
2023-02-01 7:29 ` Jean Louis
2023-02-01 7:52 ` Tim Cross
2023-02-01 8:32 ` Jean Louis
2023-02-01 8:46 ` Ihor Radchenko
2023-02-01 9:38 ` Tim Cross
2023-02-01 10:15 ` Ihor Radchenko
2023-02-01 14:53 ` Jean Louis
2023-02-01 16:36 ` Ihor Radchenko
2023-02-01 10:46 ` Max Nikulin
2023-02-01 14:43 ` Jean Louis
2023-02-01 16:45 ` Ihor Radchenko
2023-02-02 3:05 ` Max Nikulin
2023-02-02 8:59 ` Ihor Radchenko
2023-02-01 9:40 ` [POLL] Proposed syntax for timestamps with time zone info Stefan Nobis
2023-02-01 9:45 ` Ihor Radchenko
2023-02-01 14:38 ` [POLL] Proposed syntax for timestamps with time zone info (was: [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda) Jean Louis
2023-02-01 16:50 ` Ihor Radchenko
2023-02-03 15:48 ` [POLL] Proposed syntax for timestamps with time zone info Stefan Nobis
2023-02-04 5:07 ` Jean Louis
2023-02-01 9:06 ` Stefan Nobis
2023-02-01 9:20 ` tomas
2023-02-01 9:48 ` Stefan Nobis
2023-10-29 1:04 ` Jean Louis
2023-02-06 15:34 ` Marcin Borkowski
2023-02-06 17:03 ` tomas
2023-02-07 21:08 ` Jean Louis
2023-10-29 1:02 ` Jean Louis
2023-02-01 7:00 ` [POLL] Proposed syntax for timestamps with time zone info (was: [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda) Thomas S. Dye
2023-02-01 7:41 ` Jean Louis
2023-01-31 17:56 ` [POLL] Proposed syntax for timestamps with time zone info Fraga, Eric
2023-01-31 18:13 ` Ihor Radchenko
2023-01-31 18:22 ` Fraga, Eric
2023-01-31 18:56 ` [POLL] Proposed syntax for timestamps with time zone info (was: [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda) Greg Minshall
2023-02-01 12:48 ` Ihor Radchenko
2023-02-01 12:52 ` tomas
2023-02-02 4:49 ` Greg Minshall
2023-01-31 20:41 ` Tim Cross
2023-01-31 23:50 ` Samuel Wales
2023-02-01 13:01 ` Ihor Radchenko
2023-02-04 22:33 ` Samuel Wales
2023-02-04 22:49 ` Samuel Wales
2023-02-05 10:38 ` Ihor Radchenko
2023-02-01 11:56 ` Christian Moe
2023-02-01 12:20 ` Ihor Radchenko
[not found] ` <87o7qdsf7h.fsf@christianmoe.com>
2023-02-01 13:26 ` POSIX TS spec reverses the meaning of TZ offset compared to ISO (was: [POLL] Proposed syntax for timestamps with time zone info (was: [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda)) Ihor Radchenko
2023-02-01 13:51 ` tomas
2023-02-01 21:57 ` POSIX TS spec reverses the meaning of TZ offset compared to ISO (was: [POLL] Proposed syntax for timestamps with time zone info Heinz Tuechler
2023-02-01 22:50 ` Samuel Wales
2023-02-02 9:01 ` Ihor Radchenko
2023-02-02 3:22 ` Max Nikulin
2023-02-02 7:45 ` POSIX TS spec reverses the meaning of TZ offset compared to ISO Heinz Tuechler
2023-02-02 8:33 ` tomas
2023-02-02 9:37 ` Heinz Tuechler
2023-02-04 15:44 ` Max Nikulin
2023-02-02 5:35 ` POSIX TS spec reverses the meaning of TZ offset compared to ISO (was: [POLL] Proposed syntax for timestamps with time zone info tomas
2023-02-02 8:56 ` Ihor Radchenko
2023-02-01 15:16 ` POSIX TS spec reverses the meaning of TZ offset compared to ISO (was: [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda) Max Nikulin
2023-02-02 8:34 ` Ihor Radchenko
2023-02-02 13:59 ` Max Nikulin
2023-02-02 14:06 ` Ihor Radchenko
2023-02-01 15:41 ` [POLL] Proposed syntax for timestamps with time zone info " Jean Louis
2023-02-02 8:38 ` Ihor Radchenko
2023-02-03 11:31 ` Jean Louis
2023-02-04 10:58 ` Ihor Radchenko
2023-02-04 19:32 ` Jean Louis
2023-02-05 9:14 ` Ihor Radchenko
2023-02-02 3:46 ` Timothy
2023-02-02 9:12 ` Ihor Radchenko
2023-02-02 9:12 ` Timothy
2023-02-02 9:20 ` Ihor Radchenko
2023-02-02 9:27 ` Timothy
2023-02-02 9:38 ` [POLL] Proposed syntax for timestamps with time zone info Stefan Nobis
2023-01-30 12:30 ` [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda Ihor Radchenko
2023-01-30 15:30 ` Greg Minshall
2023-01-30 15:38 ` Ihor Radchenko
2023-01-30 15:48 ` Greg Minshall
2023-01-20 4:03 ` Max Nikulin
2023-01-20 5:39 ` Tim Cross
2023-01-20 7:28 ` Max Nikulin
2023-01-20 8:11 ` Tim Cross
2023-01-20 15:29 ` Max Nikulin
2023-01-20 22:56 ` Tim Cross
2023-01-20 9:35 ` Fraga, Eric
2023-01-20 10:48 ` Ihor Radchenko
2023-01-20 6:46 ` Thomas S. Dye
2023-01-20 7:34 ` Max Nikulin
2023-01-20 8:17 ` Tim Cross
2023-01-20 12:17 ` Max Nikulin
2023-01-20 16:09 ` Thomas S. Dye
2023-01-20 16:56 ` Max Nikulin
2023-01-20 20:37 ` Thomas S. Dye
2023-01-21 0:14 ` Tim Cross
2023-01-21 0:37 ` Thomas S. Dye
2023-01-21 5:53 ` Max Nikulin
2023-01-21 15:55 ` Thomas S. Dye
2023-01-22 12:14 ` Max Nikulin
2023-01-22 13:35 ` Thomas S. Dye
2023-01-22 14:09 ` Max Nikulin
2023-01-20 23:38 ` Tim Cross
2023-01-21 6:21 ` Max Nikulin
2023-01-21 21:29 ` Tim Cross
2023-01-22 5:50 ` UTC or not UTC for timestamps in the past ([FEATURE REQUEST] Timezone support in org-mode) Max Nikulin
2023-01-22 6:17 ` Thomas S. Dye
2023-01-22 8:35 ` Max Nikulin
2023-01-22 16:54 ` Thomas S. Dye
2023-01-23 6:28 ` Jean Louis
2023-01-23 16:04 ` Thomas S. Dye
2023-01-24 2:34 ` Max Nikulin
2023-01-24 2:44 ` Thomas S. Dye
2023-01-24 4:48 ` Max Nikulin
2023-01-24 19:18 ` Jean Louis
2023-01-24 9:34 ` Ihor Radchenko
2023-01-24 16:41 ` Thomas S. Dye
2023-01-26 15:37 ` Max Nikulin
2023-01-26 16:31 ` Thomas S. Dye
2023-01-27 21:21 ` Tim Cross
2023-01-22 7:48 ` Tim Cross
2023-01-24 17:09 ` Max Nikulin
2023-01-24 19:20 ` Jean Louis
2023-01-24 20:50 ` Tim Cross
2023-01-19 10:35 ` [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda Ihor Radchenko
2023-01-19 17:57 ` Alexander Adolf
2023-01-21 13:51 ` Jean Louis
2023-01-18 17:09 ` Max Nikulin
2023-01-17 8:45 ` Ihor Radchenko
2023-01-19 16:56 ` Robert Horn
2023-01-19 17:44 ` Alexander Adolf
2023-01-19 17:48 ` Alexander Adolf
2023-01-17 15:37 ` Jean Louis
2023-01-18 9:29 ` Ihor Radchenko
2023-01-18 16:11 ` Jean Louis
2023-01-18 21:31 ` Tim Cross
2023-01-19 10:40 ` Ihor Radchenko
2023-01-17 17:28 ` Max Nikulin
2023-01-17 19:49 ` Ihor Radchenko
2023-01-18 16:21 ` Jean Louis
2023-01-18 16:20 ` Jean Louis
2023-01-20 16:27 ` Max Nikulin
2023-01-19 17:33 ` Alexander Adolf
2023-01-16 20:25 ` Tim Cross
2023-01-17 9:07 ` Ihor Radchenko
2023-01-17 15:24 ` Jean Louis
2023-01-18 9:34 ` Ihor Radchenko
2023-01-18 16:07 ` Jean Louis
2023-01-19 10:43 ` Ihor Radchenko
2023-01-19 14:37 ` Jean Louis
2023-01-15 20:43 ` Jean Louis
2023-01-16 11:25 ` Ihor Radchenko
2023-01-17 15:19 ` Jean Louis
2023-01-18 9:38 ` Ihor Radchenko
2023-01-16 5:01 ` Tom Gillespie
2023-01-16 12:31 ` Ihor Radchenko
2023-01-16 20:32 ` Tim Cross
2023-01-16 20:51 ` Tom Gillespie
2023-01-17 9:12 ` [FR] Allow BC years in timestamps (was: [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda) Ihor Radchenko
2023-01-13 19:06 ` [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda Jean Louis
2023-01-14 7:12 ` Max Nikulin
2023-01-14 9:32 ` Tim Cross
2023-01-14 11:08 ` Russell Adams
2023-01-14 11:35 ` Ihor Radchenko
2023-01-14 12:00 ` Russell Adams
2023-01-14 12:16 ` [FR] Allow end date and max repeat count for timestamps with repeaters (was: [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda) Ihor Radchenko
2023-01-15 1:09 ` Samuel Wales
2023-01-15 13:45 ` Ihor Radchenko
2023-01-15 23:49 ` Samuel Wales
2023-01-15 23:53 ` Samuel Wales
2023-01-16 13:01 ` Ihor Radchenko
2023-01-14 12:19 ` [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda Ihor Radchenko
2023-01-14 12:21 ` Russell Adams
2023-01-14 12:31 ` Ihor Radchenko
2023-01-14 11:30 ` Ihor Radchenko
2023-01-14 14:09 ` Tim Cross
2023-01-14 14:38 ` Ihor Radchenko
2023-01-14 14:48 ` tomas
2023-01-14 15:05 ` Ihor Radchenko
2023-01-14 16:50 ` tomas
2023-01-14 17:06 ` Ihor Radchenko
2023-01-14 17:13 ` tomas
2023-01-15 19:54 ` Jean Louis
2023-01-14 21:52 ` Tim Cross
2023-01-15 13:52 ` Ihor Radchenko
2023-01-20 14:34 ` Alexander Adolf
2023-01-15 20:03 ` Jean Louis
2023-01-15 19:52 ` Jean Louis
2023-01-16 13:11 ` Ihor Radchenko
2023-01-14 20:56 ` Tim Cross
2023-01-15 20:24 ` Jean Louis
2023-01-15 4:37 ` Max Nikulin
2023-01-15 5:03 ` Max Nikulin
2023-01-15 20:28 ` Jean Louis
2023-01-16 13:17 ` Ihor Radchenko
2023-01-14 11:55 ` Max Nikulin
2023-01-14 13:50 ` Tim Cross
2023-01-14 16:50 ` Max Nikulin
2023-01-14 20:30 ` Tim Cross
2023-01-15 4:00 ` Max Nikulin
2023-01-15 7:53 ` Tim Cross [this message]
2023-01-15 19:26 ` Jean Louis
2023-01-16 13:20 ` Ihor Radchenko
2023-01-15 14:00 ` Ihor Radchenko
2023-01-14 13:08 ` Jean Louis
2023-01-14 16:58 ` Max Nikulin
2023-01-14 19:43 ` Tim Cross
2023-01-15 6:37 ` tomas
2023-01-15 14:07 ` Ihor Radchenko
2023-01-15 20:43 ` Tim Cross
2023-01-16 5:20 ` Tom Gillespie
2023-01-16 13:29 ` Ihor Radchenko
2023-01-16 17:30 ` Tom Gillespie
2023-01-16 17:53 ` Ihor Radchenko
2023-01-16 13:27 ` Ihor Radchenko
2023-01-15 19:14 ` Jean Louis
2023-01-16 4:20 ` Max Nikulin
2023-01-15 19:12 ` Jean Louis
2023-01-14 5:14 ` Samuel Wales
2023-01-14 5:51 ` Tom Gillespie
2023-01-14 6:40 ` tomas
2023-01-26 15:24 ` Org mode timestamps on the Moon ;] (was: [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda) Ihor Radchenko
2023-01-26 16:08 ` Org mode timestamps on the Moon ;] Fraga, Eric
2023-01-26 16:28 ` Thomas S. Dye
2023-01-26 23:40 ` Org mode timestamps on the Moon ;] (was: [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda) Tom Gillespie
2023-01-30 10:13 ` Org mode timestamps on the Moon ; ] " Greg Minshall
2023-01-30 13:05 ` Org mode timestamps on the Moon ;] " Ihor Radchenko
-- strict thread matches above, loose matches on Subject: below --
2023-01-15 19:16 [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda Thomas S. Dye
2023-01-28 6:26 Max Nikulin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: https://www.orgmode.org/
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=63c3b1a4.a70a0220.225b1.83fe@mx.google.com \
--to=theophilusx@gmail.com \
--cc=emacs-orgmode@gnu.org \
--cc=manikulin@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://git.savannah.gnu.org/cgit/emacs/org-mode.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).