Greetings, Although Ethiopia is officially in East Africa Time (UTC +3:00), the local time used in the country adopts a different system where 6:00 AM is interpreted as 12:00 and socially used as such. People will see a clock with the time at 1:30, and they will say this is 7:30. The local time is used by businesses in the country and by government offices. Everyone generally does this conversion in their heads, so at times, someone who is unfamiliar with this system can end up inadvertently scheduling meetings for the wrong time. This method of time tracking was developed and maintained with the premise of associating the clock's starting point of 12:00 with sunrise, which is roughly taking place around 6:00 AM every day. So East Africa Time - 6:00 is the working time used by the vast majority of Ethiopians. Here's an article discussing this time system: https://www.pri.org/stories/2015-01-30/if-you-have-meeting-ethiopia-you-bett... Is it possible to include Ethiopia's local time system into the time zone database? If so, what are the requirements for submitting a new time zone? Thanks for your consideration. Regards, Khalid Duri
admin@afocha.com wrote:
Is it possible to include Ethiopia's local time system into the time zone database?
I'm afraid not, as it's based on solar time. We used to attempt to do this sort of thing for Saudi Arabia, but gave up because to do it right we'd need a separate table for each geographical location, multiplied by the number of timekeeping practices (not everybody does things the same way in either Saudi Arabia or in Ethiopia, as I understand it), and it's impractical to do this sort of thing for either country. As luck would have it, we recently added some documentation about this for Saudi Arabia here: https://github.com/eggert/tz/commit/da31293a319ba5227342e236bcdadaf5d288e1f3 It makes sense to do something similar for Ethiopia, so I installed the attached proposed patch to the development version. Thanks for the citation.
On Tue 2018-09-11T22:23:01-0700 Paul Eggert hath writ:
I'm afraid not, as it's based on solar time.
The article gives the impression that it's not really solar because an hour of imprecision is culturally irrelevant, so it's really just 6 hours different from what a cell phone says. But even with that simplicity I don't think that tz should implement something without a much more authoritative and clear source for when the Ethiopian day begins. -- Steve Allen <sla@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
On Sep 12, 2018, at 3:58 PM, Steve Allen <sla@ucolick.org> wrote:
On Tue 2018-09-11T22:23:01-0700 Paul Eggert hath writ:
I'm afraid not, as it's based on solar time.
The article gives the impression that it's not really solar because an hour of imprecision is culturally irrelevant, so it's really just 6 hours different from what a cell phone says. But even with that simplicity I don't think that tz should implement something without a much more authoritative and clear source for when the Ethiopian day begins.
-- Steve Allen <sla@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
That brings up an interesting question. What does the TZ database mean "local time" to be? Time in its common representation where zero is midnight and 12 o'clock is noon? Or is it meant to account also for local conventions that zero is some point in the day different from midnight? If the former, then this issue is out of scope. If the latter, then it suggests there might be two Ethiopia zones, one for "midnight origin" (the one we have now) and one for "local convention" which combines the offsets from latitude, and the offset from the different convention of what the starting point is. paul
Keep in mind that if 'local convention' is 6:00am is synchronized to sunrise then the time changes every day since sunrise time is different every day (usually by about a minute or 2 but that depends of the time of the year). That would have the consequence that every day could be slightly longer or shorter than 24h and that DST shift would occur every day. More over the time of DST shift would be variable since sunrise is. And if we care to be accurate to the millisecond, you need to know the actual longitude since that time variation of sunrise is a continuous phenomena and therefore the time of shift of DST in the east of the country would be different than the one in the west of the country with respect to UT for any given day. On 12/09/2018 4:05 PM, Paul.Koning@dell.com wrote:
What does the TZ database mean "local time" to be? Time in its common representation where zero is midnight and 12 o'clock is noon? Or is it meant to account also for local conventions that zero is some point in the day different from midnight?
If the former, then this issue is out of scope. If the latter, then it suggests there might be two Ethiopia zones, one for "midnight origin" (the one we have now) and one for "local convention" which combines the offsets from latitude, and the offset from the different convention of what the starting point is.
paul
-- Oracle Email Signature Logo Patrice Scattolin | Software Development Manager | 514.905.8744 Oracle Cloud 600 Blvd de Maisonneuve West Suite 1900 Montreal, Quebec
Per the "Theory" file: "...the world is partitioned into regions whose clocks all agree..." So at least at the moment, the goal is to reflect what clocks say the time is rather than what people say the time is. That goal is, of course, subject to change. @dashdashado On Wed, Sep 12, 2018 at 4:24 PM Patrice Scattolin < patrice.scattolin@oracle.com> wrote:
Keep in mind that if 'local convention' is 6:00am is synchronized to sunrise then the time changes every day since sunrise time is different every day (usually by about a minute or 2 but that depends of the time of the year). That would have the consequence that every day could be slightly longer or shorter than 24h and that DST shift would occur every day. More over the time of DST shift would be variable since sunrise is.
And if we care to be accurate to the millisecond, you need to know the actual longitude since that time variation of sunrise is a continuous phenomena and therefore the time of shift of DST in the east of the country would be different than the one in the west of the country with respect to UT for any given day.
On 12/09/2018 4:05 PM, Paul.Koning@dell.com wrote:
What does the TZ database mean "local time" to be? Time in its common representation where zero is midnight and 12 o'clock is noon? Or is it meant to account also for local conventions that zero is some point in the day different from midnight?
If the former, then this issue is out of scope. If the latter, then it suggests there might be two Ethiopia zones, one for "midnight origin" (the one we have now) and one for "local convention" which combines the offsets from latitude, and the offset from the different convention of what the starting point is.
paul
--
[image: Oracle Email Signature Logo] Patrice Scattolin | Software Development Manager | 514.905.8744 Oracle Cloud 600 Blvd de Maisonneuve West Suite 1900 Montreal, Quebec
On Wed 2018-09-12T16:58:39-0400 Arthur David Olson hath writ:
Per the "Theory" file: "...the world is partitioned into regions whose clocks all agree..." So at least at the moment, the goal is to reflect what clocks say the time is rather than what people say the time is. That goal is, of course, subject to change.
It would be useful to know if privately set clocks and wristwatches commonly use this 6 hour offset. If that is the case then it seems that Ethiopia is much the same as Asia/Urumqi -- Steve Allen <sla@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
The system is also used in Kenya, Ethiopia's neighbour. If you ask anyone in Swahili what time lunch is, they say 'six o'clock'. On 2018-09-12 17:41, Steve Allen wrote:
On Wed 2018-09-12T16:58:39-0400 Arthur David Olson hath writ:
Per the "Theory" file: "...the world is partitioned into regions whose clocks all agree..." So at least at the moment, the goal is to reflect what clocks say the time is rather than what people say the time is. That goal is, of course, subject to change. It would be useful to know if privately set clocks and wristwatches commonly use this 6 hour offset. If that is the case then it seems that Ethiopia is much the same as Asia/Urumqi
-- Steve Allen <sla@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
But if you ask them in English, they say '12 o'clock'. If they wear a watch, it uses 'English time', and is set with midnight/noon at twelve. But they subtract 6 from 'English time' time when speaking Swahili and their own tribal languages. On 2018-09-12 18:03, David Patte wrote:
The system is also used in Kenya, Ethiopia's neighbour. If you ask anyone in Swahili what time lunch is, they say 'six o'clock'.
On 2018-09-12 17:41, Steve Allen wrote:
On Wed 2018-09-12T16:58:39-0400 Arthur David Olson hath writ:
Per the "Theory" file: "...the world is partitioned into regions whose clocks all agree..." So at least at the moment, the goal is to reflect what clocks say the time is rather than what people say the time is. That goal is, of course, subject to change. It would be useful to know if privately set clocks and wristwatches commonly use this 6 hour offset. If that is the case then it seems that Ethiopia is much the same as Asia/Urumqi
-- Steve Allen <sla@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
For what it's worth, CLDR is tracking this issue at https://unicode.org/cldr/trac/ticket/9716 — my current thinking is to have something called a "time cycle", but it would be applied on top of the time zone calculation. Supporting it if it were UTC-3 has other problems. I think it should be considered a localization and not a time zone issue. Steven On Wed, Sep 12, 2018 at 3:14 PM David Patte <dpatte@relativedata.com> wrote:
But if you ask them in English, they say '12 o'clock'. If they wear a watch, it uses 'English time', and is set with midnight/noon at twelve. But they subtract 6 from 'English time' time when speaking Swahili and their own tribal languages.
On 2018-09-12 18:03, David Patte wrote:
The system is also used in Kenya, Ethiopia's neighbour. If you ask anyone in Swahili what time lunch is, they say 'six o'clock'.
On 2018-09-12 17:41, Steve Allen wrote:
On Wed 2018-09-12T16:58:39-0400 Arthur David Olson hath writ:
Per the "Theory" file: "...the world is partitioned into regions whose clocks all agree..." So at least at the moment, the goal is to reflect what clocks say the time is rather than what people say the time is. That goal is, of course, subject to change. It would be useful to know if privately set clocks and wristwatches commonly use this 6 hour offset. If that is the case then it seems that Ethiopia is much the same as Asia/Urumqi
-- Steve Allen <sla@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
Hi Steven, can you expand on some of the problems that can be anticipated with using UTC-3? On Wed, Sep 12, 2018 at 3:43 PM Steven R. Loomis <srl@icu-project.org> wrote:
For what it's worth, CLDR is tracking this issue at https://unicode.org/cldr/trac/ticket/9716 — my current thinking is to have something called a "time cycle", but it would be applied on top of the time zone calculation. Supporting it if it were UTC-3 has other problems.
I think it should be considered a localization and not a time zone issue.
Steven
On Wed, Sep 12, 2018 at 3:14 PM David Patte <dpatte@relativedata.com> wrote:
But if you ask them in English, they say '12 o'clock'. If they wear a watch, it uses 'English time', and is set with midnight/noon at twelve. But they subtract 6 from 'English time' time when speaking Swahili and their own tribal languages.
On 2018-09-12 18:03, David Patte wrote:
The system is also used in Kenya, Ethiopia's neighbour. If you ask anyone in Swahili what time lunch is, they say 'six o'clock'.
On 2018-09-12 17:41, Steve Allen wrote:
On Wed 2018-09-12T16:58:39-0400 Arthur David Olson hath writ:
Per the "Theory" file: "...the world is partitioned into regions whose clocks all agree..." So at least at the moment, the goal is to reflect what clocks say the time is rather than what people say the time is. That goal is, of course, subject to change. It would be useful to know if privately set clocks and wristwatches commonly use this 6 hour offset. If that is the case then it seems that Ethiopia is much the same as Asia/Urumqi
-- Steve Allen <sla@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
-- This email communication is intended as a private communication for the sole use of the primary addressee and the recipients listed in the original message. If you are not an intended recipient, you are hereby notified that distribution of this communication by any means is prohibited. Please notify the sender if you are not specifically authorized to receive this email and have received it in error.
Sure, off the top of my head: • Time zone is often associated with a specific user in a particular location. multiple *calendar* systems are commonly shown in parallel within one UI, sometimes within the same string. For devices (say a desktop or mobile computer, or a physical clock) there is usually a single setting for time zone. All of this to say, that the 'western' and 'ethiopian' [1] systems should be shown side by side, on a single device that currently would only have a single time zone. • As opposed to the division AM/PM, there are time periods that need to be used ( see https://unicode.org/cldr/trac/ticket/8473 ) such as "ከሰዓት - afternoon - 6:01 to 11:59 Ethiopic = 12:01 to 17:59 Gregorian" which need to be calculated based on local timezone-adjusted time. If the time zone were skewed by 6 hours then the period would be off. • It also wasn't clear if the day-of-month boundary would necessary follow the adjusted time. A 'simple' TZ offset doesn't allow this flexibility. • there are other hour cycle systems (day start at sunset, astronomical julian day start at noon etc) and so more flexibility is needed in general. • for software use, our APIs (ICU) return timezone information separate from time of day calculation. I know that wearing a watch upside-down is done in some places, but this may also not be optimal. Hope this helps, Steven - [1] we definitely need better terms here— this system is certainly used outside of ethiopia. I use the term 'western' because that is what I have seen used contrastively with the 'ethiopian' system. On Wed, Sep 12, 2018 at 3:46 PM Khalid H. Duri <zewari@gmail.com> wrote:
Hi Steven, can you expand on some of the problems that can be anticipated with using UTC-3? On Wed, Sep 12, 2018 at 3:43 PM Steven R. Loomis <srl@icu-project.org> wrote:
For what it's worth, CLDR is tracking this issue at
https://unicode.org/cldr/trac/ticket/9716 — my current thinking is to have something called a "time cycle", but it would be applied on top of the time zone calculation. Supporting it if it were UTC-3 has other problems.
I think it should be considered a localization and not a time zone issue.
Steven
On Wed, Sep 12, 2018 at 3:14 PM David Patte <dpatte@relativedata.com>
wrote:
But if you ask them in English, they say '12 o'clock'. If they wear a watch, it uses 'English time', and is set with midnight/noon at twelve. But they subtract 6 from 'English time' time when speaking Swahili and their own tribal languages.
On 2018-09-12 18:03, David Patte wrote:
The system is also used in Kenya, Ethiopia's neighbour. If you ask anyone in Swahili what time lunch is, they say 'six o'clock'.
On 2018-09-12 17:41, Steve Allen wrote:
On Wed 2018-09-12T16:58:39-0400 Arthur David Olson hath writ:
Per the "Theory" file: "...the world is partitioned into regions
whose
clocks all agree..." So at least at the moment, the goal is to reflect what clocks say the time is rather than what people say the time is. That goal is, of course, subject to change. It would be useful to know if privately set clocks and wristwatches commonly use this 6 hour offset. If that is the case then it seems that Ethiopia is much the same as Asia/Urumqi
-- Steve Allen <sla@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
-- This email communication is intended as a private communication for the sole use of the primary addressee and the recipients listed in the original message. If you are not an intended recipient, you are hereby notified that distribution of this communication by any means is prohibited. Please notify the sender if you are not specifically authorized to receive this email and have received it in error.
On 9/12/18 3:42 PM, Steven R. Loomis wrote:
CLDR is tracking this issue at https://unicode.org/cldr/trac/ticket/9716 — my current thinking is to have something called a "time cycle", but it would be applied on top of the time zone calculation. Supporting it if it were UTC-3 has other problems.
I think it should be considered a localization and not a time zone issue.
That makes sense. It's a clearer way to address the issue, and I do see the resemblance to the issue of Japanese times that go past 24:00. My understanding, by the way, is that it's not as simple as saying that 06:00 western time is equivalent to 00:00 Ethiopian time the same day, and that Western and Ethiopian clocks tick at the same rate. Although that is common practice in business in the major cities (and no doubt cell phones have a lot to do with this), it's an approximation of a tradition that is also mentioned in Mortada's PRI story, which is that each day and night is divided into 12 equal hours, and that summer days and winter nights have longer hours. Ethiopia is close enough to the equator that the modern business approximation is reasonably close, but it is just an approximation. Before cell phones became ubiquitous, as I undertand it, people set their watches to 12 o'clock at dawn: although this is a better approximation to tradition than the simpler "subtract 6 hours" method used with cell phones, it's still just an approximation. Just to make things more interesting, I've also been told that some people in Ethiopia set their watches to 6 o'clock at dawn, which would be yet another compromise between traditional and Western timekeeping. Sorry, I don't know the details about this (e.g., is it done only in some regions, or is it more an ethnic-group thing?). If you have a cell phone, there are apps that will display Ethiopian business time, and to some extent these can fill in for CLDR and/or tzdb. I don't know if these apps agree about the timekeeping details, though (such as exactly when the date ticks over). See: https://play.google.com/store/apps/details?id=com.addistag.time https://itunes.apple.com/us/app/ethiopia-time-ethiopian-12-hour-clock/id7939...
On Sep 12, 2018, at 3:42 PM, Steven R. Loomis <srl@icu-project.org> wrote:
For what it's worth, CLDR is tracking this issue at https://unicode.org/cldr/trac/ticket/9716 — my current thinking is to have something called a "time cycle", but it would be applied on top of the time zone calculation. Supporting it if it were UTC-3 has other problems.
I think it should be considered a localization and not a time zone issue.
And, for what it's worth, the original client of the tzdb, and still one of the major clients of the tzdb, is the localtime() routine; the C90 standard says: 7.12 Date and time <time.h> 7.12.1 Components of time The header <time.h> defines two macros, and declares four types and several functions for manipulating time. Many functions deal with a calendar time that represents the current date (according to the Gregorian calendar) and time. Some functions deal with local time, which is the calendar time expressed for some specific time zone, and with Daylight Saving Time, which is a temporary change in the algorithm for determining local time. The local time zone and Daylight Saving Time are implementation-defined. ... The types declared are size_t (described in 7.1.6); ... ... and struct tm which holds the components of a calendar time, called the broken-down time. The structure shall contain at least the following members, in any order. The semantics of the members and their normal ranges are expressed in the comments. ... int tm_hour; /* hours since midnight — [0 23] */ ... This means that tm_hour has to be 0 at midnight, even if people in some locale call it 6:00 or 18:00, just as it has to be 0 at midnight, even though people in some locale call it 12:00 AM. So I agree that this is a localization issue, and that APIs for displaying time for human purposes should support showing midnight as 6:00 (or whatever form is used in those locales) if those APIs are sufficiently localized to support a 12-hour clock (i.e., if you can show USans midnight as 12:00 AM, you should also be able to show Ethiopians midnight as 6:00 or 18:00 or however it's displayed there).
On Wed 2018-09-12T16:20:53-0700 Guy Harris hath writ:
int tm_hour; /* hours since midnight — [0 23] */
This means that tm_hour has to be 0 at midnight
I think this means that the hour has to be 0 when the calendar date changes. The meaning is the number of hours since the change of the calendar date, and in the usage prescribed by the 1884 International Meridian Conference that has been midnight. If the Ethiopian common use of time and date has the calendar change at sunrise or sunset then the POSIX requirements are satisfied. -- Steve Allen <sla@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
When does the date change? In the middle of the night or around dawn?
The new day begins when the hour strikes 6:00 AM EAT, or 12:00 local time. From my preliminary research, the same method of conveying date and time is used in Ethiopia, Kenya, and Somalia, but not Somaliland and Djibouti.
Then, if we say Ethiopia is UTC-3, then clocks that automatically follow tz database would be shifted 6 hours, and thus when local people say it is 6 o'clock in local languages, the clock would display as 🕕 instead. However it would seems like it would confuse people, as according to the description, people who use watches and speak local language in that part of the world are still setting their clock to the UTC+3 timezone.
I believe the locals do this to conform to the international standard and the lack of formal recognition of the local system for tracking the transition of days and time. I am not sure about other countries, but in Ethiopia, this system is not just a colloquial detail, but a working system that is poorly managed by software. I think the likelihood of a localization pack addressing this for multiple software products is highly unlikely.
As opposed to the division AM/PM, there are time periods that need to be used ( see https://unicode.org/cldr/trac/ticket/8473 [1] ) such as " ከሰዓት - afternoon - 6:01 to 11:59 Ethiopic = 12:01 to 17:59 Gregorian" which need to be calculated based on local timezone-adjusted time. If the time zone were skewed by 6 hours then the period would be off.
An AM/PM designation would still work in that it is straight forward and would get adopted as a compromise. I will contact the Ministry of Science and Technology to get their thoughts on the subject. Regards, Khalid ----- Original Message ----- From: "Steve Allen" <sla@ucolick.org> On Wed 2018-09-12T16:20:53-0700 Guy Harris hath writ:
int tm_hour; /* hours since midnight — [0 23] */
This means that tm_hour has to be 0 at midnight
I think this means that the hour has to be 0 when the calendar date changes. The meaning is the number of hours since the change of the calendar date, and in the usage prescribed by the 1884 International Meridian Conference that has been midnight. If the Ethiopian common use of time and date has the calendar change at sunrise or sunset then the POSIX requirements are satisfied. -- Steve Allen <sla@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m Links: ------ [1] https://unicode.org/cldr/trac/ticket/8473
admin@afocha.com said:
When does the date change? In the middle of the night or around dawn?
The new day begins when the hour strikes 6:00 AM EAT, or 12:00 local time.
So around dawn. In that case this looks like people are working on zone -3 instead of +3. So it would make sense to have it in the TZ database. It's not just a rewrite of the times (like the 12/24 hour example). -- Clive D.W. Feather | If you lie to the compiler, Email: clive@davros.org | it will get its revenge. Web: http://www.davros.org | - Henry Spencer Mobile: +44 7973 377646
- So if I understand it correctly, when everyone look at the watchface of 🕕 (let me use emoji for clearer representation here) and they will say it is 12 o'clock in local language, and then when everyone look at the watchface of 🕛 and they will say it is 6 o'clock in local language. - Then, if we say Ethiopia is UTC-3, then clocks that automatically follow tz database would be shifted 6 hours, and thus when local people say it is 6 o'clock in local languages, the clock would display as 🕕 instead. However it would seems like it would confuse people, as according to the description, people who use watches and speak local language in that part of the world are still setting their clock to the UTC+3 timezone. - Is it correct to say it is more of a "translation" problem than time-keeping problem, where "6 o'clock in local language" mean "12 o'clock in English"? - Is it correct to think it is similar to English, where December is Dec which mean the tenth despite being the 12th month? - When would a new day start according to the local language convention? 2018-9-13 06:14, David Patte <dpatte@relativedata.com> wrote:
But if you ask them in English, they say '12 o'clock'. If they wear a watch, it uses 'English time', and is set with midnight/noon at twelve. But they subtract 6 from 'English time' time when speaking Swahili and their own tribal languages.
On 2018-09-13 00:52, Phake Nick wrote:
- Is it correct to think it is similar to English, where December is Dec which mean the tenth despite being the 12th month? TL;DR: Those months are derived from the Latin used by the Roman church which provided the clerks who originally constructed calendars, assigned saints' days and holy days, and recorded business and events according to their calendar.
-- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada This email may be disturbing to some readers as it contains too much technical detail. Reader discretion is advised. [OT] The primitive Roman calendar started in spring like many others, and did not name the winter months; later they were added to the end of the year as Ianuarius and Februarius, with the leap day correction added at the start of the last week of February; then the start of the year was shifted from the end of the winter months to the start of the winter months; although the year number did not change until spring (the Hebrew calendar still does something like this, as may others). After the change to the Gregorian calendar, some important legal days were shifted so they occurred 365/366 days after the previous occurrence of that day on the old calendar (including birth dates amd anniversaries), where others were held to occur on the same month and date as on the old calendar, and the year numbering changed at the start of January.
Brian Inglis said:
After the change to the Gregorian calendar, some important legal days were shifted so they occurred 365/366 days after the previous occurrence of that day on the old calendar (including birth dates amd anniversaries), where others were held to occur on the same month and date as on the old calendar, and the year numbering changed at the start of January.
Depends where you were. In England, in legal time, that was true: years up to 1751 started on 25th March and those from 1752 onwards started on 1st January (the switch to Gregorian happened in September 1752). But in Scotland, and for that matter in common practice in England, the year changed on 1st January already. -- Clive D.W. Feather | If you lie to the compiler, Email: clive@davros.org | it will get its revenge. Web: http://www.davros.org | - Henry Spencer Mobile: +44 7973 377646
On 2018-09-14 15:11, Clive D.W. Feather wrote:
Brian Inglis said:
After the change to the Gregorian calendar, some important legal days were shifted so they occurred 365/366 days after the previous occurrence of that day on the old calendar (including birth dates amd anniversaries), where others were held to occur on the same month and date as on the old calendar, and the year numbering changed at the start of January.
Depends where you were. In England, in legal time, that was true: years up to 1751 started on 25th March and those from 1752 onwards started on 1st January (the switch to Gregorian happened in September 1752). But in Scotland, and for that matter in common practice in England, the year changed on 1st January already.
Year 1599 lasted only from April-December and January 1 became 1600 instead: https://www.nrscotland.gov.uk/research/record-guides/old-parish-registers/ch... James VI/I regnal year dating was probably also dual after 1603. -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada This email may be disturbing to some readers as it contains too much technical detail. Reader discretion is advised.
Greetings everyone, Thanks for the replies! The time is not adjusted for the exact sunrise of each day, but rather consistently applied as -6:00 on East Africa Standard Time. In the context of Ethiopia, this adjustment is widely used in business and government activities. People will use the EAT time when speaking to someone they see as a foreigner, but if you live in the country for some time, you are expected to internalize this time system. Incorporating this as a formal time zone would allow for the local norm for telling time to be modernized. Given that it is a static shift and not based on actual sunrise, what is the barrier to legitimizing this as a formal time zone? What would be considered an authoritative basis for incorporating this as a time zone? Another person on the mailing list replied to me noting that the same type of adjustment is often used in Kenya, which is also in the same time zone as Ethiopia. I will check with my contacts in Sudan and Somalia and see if the same convention applies in those places. Regards, Khalid ----- Original Message ----- From: "Patrice Scattolin" <patrice.scattolin@oracle.com> To: <tz@iana.org> Cc: Sent: Wed, 12 Sep 2018 16:23:36 -0400 Subject: Re: [tz] Ethiopia local time Keep in mind that if 'local convention' is 6:00am is synchronized to sunrise then the time changes every day since sunrise time is different every day (usually by about a minute or 2 but that depends of the time of the year). That would have the consequence that every day could be slightly longer or shorter than 24h and that DST shift would occur every day. More over the time of DST shift would be variable since sunrise is. And if we care to be accurate to the millisecond, you need to know the actual longitude since that time variation of sunrise is a continuous phenomena and therefore the time of shift of DST in the east of the country would be different than the one in the west of the country with respect to UT for any given day. On 12/09/2018 4:05 PM, Paul.Koning@dell.com [1] wrote: What does the TZ database mean "local time" to be? Time in its common representation where zero is midnight and 12 o'clock is noon? Or is it meant to account also for local conventions that zero is some point in the day different from midnight? If the former, then this issue is out of scope. If the latter, then it suggests there might be two Ethiopia zones, one for "midnight origin" (the one we have now) and one for "local convention" which combines the offsets from latitude, and the offset from the different convention of what the starting point is. paul -- Patrice Scattolin | Software Development Manager | 514.905.8744 Oracle Cloud 600 Blvd de Maisonneuve West Suite 1900 Montreal, Quebec Links: ------ [1] mailto:Paul.Koning@dell.com
admin@afocha.com said:
Thanks for the replies! The time is not adjusted for the exact sunrise of each day, but rather consistently applied as -6:00 on East Africa Standard Time. In the context of Ethiopia, this adjustment is widely used in business and government activities.
When does the date change? In the middle of the night or around dawn? -- Clive D.W. Feather | If you lie to the compiler, Email: clive@davros.org | it will get its revenge. Web: http://www.davros.org | - Henry Spencer Mobile: +44 7973 377646
On 2018-09-13 06:25:41 (+0200), Clive D.W. Feather wrote:
admin@afocha.com said:
Thanks for the replies! The time is not adjusted for the exact sunrise of each day, but rather consistently applied as -6:00 on East Africa Standard Time. In the context of Ethiopia, this adjustment is widely used in business and government activities.
When does the date change? In the middle of the night or around dawn?
According to friends from Kenya: the date changes at "6 o'clock at night": so at midnight EAT. Philip -- Philip Paeps Senior Reality Engineer Ministry of Information
To bring this back, then, to a recognition of the potential differences in how the hours are counted, we should probably expand the text in theory slightly to specify that tz counts hours under the assumption that 00 represents midnight. Proposed patch attached. -- Tim Parenti On Thu, 4 Oct 2018 at 02:37, Philip Paeps <philip@trouble.is> wrote:
On 2018-09-13 06:25:41 (+0200), Clive D.W. Feather wrote:
admin@afocha.com said:
Thanks for the replies! The time is not adjusted for the exact sunrise of each day, but rather consistently applied as -6:00 on East Africa Standard Time. In the context of Ethiopia, this adjustment is widely used in business and government activities.
When does the date change? In the middle of the night or around dawn?
According to friends from Kenya: the date changes at "6 o'clock at night": so at midnight EAT.
Philip
-- Philip Paeps Senior Reality Engineer Ministry of Information
On Thu 2018-10-04T18:13:56-0400 Tim Parenti hath writ:
To bring this back, then, to a recognition of the potential differences in how the hours are counted, we should probably expand the text in theory slightly to specify that tz counts hours under the assumption that 00 represents midnight.
I think that 00 represents the hour at which the calendar day and date change. That may not happen in the middle of the night. -- Steve Allen <sla@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
For tz's purposes, though (the sentence begins "The tz database models time using…"), those are synonymous. Of course, this may not be the case if you're using a workaround like the one suggested for Ethiopia, but the goal is to further clarify that that's out of our scope. -- Tim Parenti On Thu, 4 Oct 2018 at 19:14, Steve Allen <sla@ucolick.org> wrote:
On Thu 2018-10-04T18:13:56-0400 Tim Parenti hath writ:
To bring this back, then, to a recognition of the potential differences in how the hours are counted, we should probably expand the text in theory slightly to specify that tz counts hours under the assumption that 00 represents midnight.
I think that 00 represents the hour at which the calendar day and date change. That may not happen in the middle of the night.
-- Steve Allen <sla@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
That's not really the case. If some country decided to actually implement a year-round +6 DST, then that would also be included in tz database 2018-10-5 07:48, Tim Parenti <tim@timtimeonline.com> wrote:
For tz's purposes, though (the sentence begins "The tz database models time using…"), those are synonymous. Of course, this may not be the case if you're using a workaround like the one suggested for Ethiopia, but the goal is to further clarify that that's out of our scope.
-- Tim Parenti
On Thu, 4 Oct 2018 at 19:14, Steve Allen <sla@ucolick.org> wrote:
On Thu 2018-10-04T18:13:56-0400 Tim Parenti hath writ:
To bring this back, then, to a recognition of the potential differences in how the hours are counted, we should probably expand the text in theory slightly to specify that tz counts hours under the assumption that 00 represents midnight.
I think that 00 represents the hour at which the calendar day and date change. That may not happen in the middle of the night.
-- Steve Allen <sla@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
Sure, but the notion of "wall-clock midnight" under year-round +6 DST is no more or less tied to actual solar midnight than for any other zone as they exist today. As Steve puts it, hour 00 just represents the hour at which the calendar date changes. In your extreme example, it may seem odd to say it's midnight when the sun is still setting — and I'm certainly not suggesting Ethiopians would actually do anything remotely similar But these discrepancies don't stop folks from referring to 00:00 local time as "midnight" in most of the cases we cover, even if it… well… isn't. Moreover, we already make explicit this convention (tying hour 00 to the Western cultural notion of "midnight") elsewhere: https://github.com/eggert/tz/blob/b709eb84eaa48354186d4a11c86395e399f19c12/z... Again, I won't be bothered if it's left out, but I also haven't really seen any reason against such a clarification. Perhaps my proposed wording is not the best. -- Tim Parenti On Thu, 4 Oct 2018 at 23:49, Phake Nick <c933103@gmail.com> wrote:
That's not really the case. If some country decided to actually implement a year-round +6 DST, then that would also be included in tz database
2018-10-5 07:48, Tim Parenti <tim@timtimeonline.com> wrote:
For tz's purposes, though (the sentence begins "The tz database models time using…"), those are synonymous. Of course, this may not be the case if you're using a workaround like the one suggested for Ethiopia, but the goal is to further clarify that that's out of our scope.
-- Tim Parenti
On Thu, 4 Oct 2018 at 19:14, Steve Allen <sla@ucolick.org> wrote:
On Thu 2018-10-04T18:13:56-0400 Tim Parenti hath writ:
To bring this back, then, to a recognition of the potential differences in how the hours are counted, we should probably expand the text in theory slightly to specify that tz counts hours under the assumption that 00 represents midnight.
I think that 00 represents the hour at which the calendar day and date change. That may not happen in the middle of the night.
-- Steve Allen <sla@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
Wait a moment, I thought the term "midnight" usually refer to middle of the night instead of the 00 hours? 2018-10-6 06:52,Tim Parenti <tim@timtimeonline.com> wrote:
Sure, but the notion of "wall-clock midnight" under year-round +6 DST is no more or less tied to actual solar midnight than for any other zone as they exist today. As Steve puts it, hour 00 just represents the hour at which the calendar date changes.
In your extreme example, it may seem odd to say it's midnight when the sun is still setting — and I'm certainly not suggesting Ethiopians would actually do anything remotely similar But these discrepancies don't stop folks from referring to 00:00 local time as "midnight" in most of the cases we cover, even if it… well… isn't.
Moreover, we already make explicit this convention (tying hour 00 to the Western cultural notion of "midnight") elsewhere: https://github.com/eggert/tz/blob/b709eb84eaa48354186d4a11c86395e399f19c12/z...
Again, I won't be bothered if it's left out, but I also haven't really seen any reason against such a clarification. Perhaps my proposed wording is not the best.
-- Tim Parenti
On Thu, 4 Oct 2018 at 23:49, Phake Nick <c933103@gmail.com> wrote:
That's not really the case. If some country decided to actually implement a year-round +6 DST, then that would also be included in tz database
2018-10-5 07:48, Tim Parenti <tim@timtimeonline.com> wrote:
For tz's purposes, though (the sentence begins "The tz database models time using…"), those are synonymous. Of course, this may not be the case if you're using a workaround like the one suggested for Ethiopia, but the goal is to further clarify that that's out of our scope.
-- Tim Parenti
On Thu, 4 Oct 2018 at 19:14, Steve Allen <sla@ucolick.org> wrote:
On Thu 2018-10-04T18:13:56-0400 Tim Parenti hath writ:
To bring this back, then, to a recognition of the potential differences in how the hours are counted, we should probably expand the text in theory slightly to specify that tz counts hours under the assumption that 00 represents midnight.
I think that 00 represents the hour at which the calendar day and date change. That may not happen in the middle of the night.
-- Steve Allen <sla@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
That's not really a coherent argument against the proposal. It *can* mean that — and of course once did, approximately — but anymore, it generally doesn't, and there's little correlation between the two. Where I live, at this time of year, "solar midnight" is approximately 01:07 local time, but if I just say "midnight" to any of my friends or colleagues, they know unambiguously that I'm referring to the time-of-day when the wall clocks say 00:00, regardless of where the sun might be at that time. (Although, in any given social context, it might more accurately refer to 24:00 on a *particular* day, that's ultimately just the same time-of-day expressed differently.) There would no confusion that I might mean "solar midnight" or even "standard midnight" unless I were in very particular technical settings. I'm not sure how the Ethiopian words for "midnight" and "noon" translate, but the fact that they would number those both as 6 (in a 12-hour system) is what the extra specificity is trying to communicate is (presently) out-of-scope: tz effectively "counts" from 00 at midnight (not considering DST changes), and we already state as much elsewhere. -- Tim Parenti On Sat, 6 Oct 2018 at 04:09, Phake Nick <c933103@gmail.com> wrote:
Wait a moment, I thought the term "midnight" usually refer to middle of the night instead of the 00 hours?
2018-10-6 06:52,Tim Parenti <tim@timtimeonline.com> wrote:
Sure, but the notion of "wall-clock midnight" under year-round +6 DST is no more or less tied to actual solar midnight than for any other zone as they exist today. As Steve puts it, hour 00 just represents the hour at which the calendar date changes.
In your extreme example, it may seem odd to say it's midnight when the sun is still setting — and I'm certainly not suggesting Ethiopians would actually do anything remotely similar But these discrepancies don't stop folks from referring to 00:00 local time as "midnight" in most of the cases we cover, even if it… well… isn't.
Moreover, we already make explicit this convention (tying hour 00 to the Western cultural notion of "midnight") elsewhere: https://github.com/eggert/tz/blob/b709eb84eaa48354186d4a11c86395e399f19c12/z...
Again, I won't be bothered if it's left out, but I also haven't really seen any reason against such a clarification. Perhaps my proposed wording is not the best.
-- Tim Parenti
On Thu, 4 Oct 2018 at 23:49, Phake Nick <c933103@gmail.com> wrote:
That's not really the case. If some country decided to actually implement a year-round +6 DST, then that would also be included in tz database
2018-10-5 07:48, Tim Parenti <tim@timtimeonline.com> wrote:
For tz's purposes, though (the sentence begins "The tz database models time using…"), those are synonymous. Of course, this may not be the case if you're using a workaround like the one suggested for Ethiopia, but the goal is to further clarify that that's out of our scope.
-- Tim Parenti
On Thu, 4 Oct 2018 at 19:14, Steve Allen <sla@ucolick.org> wrote:
On Thu 2018-10-04T18:13:56-0400 Tim Parenti hath writ:
To bring this back, then, to a recognition of the potential differences in how the hours are counted, we should probably expand the text in theory slightly to specify that tz counts hours under the assumption that 00 represents midnight.
I think that 00 represents the hour at which the calendar day and date change. That may not happen in the middle of the night.
-- Steve Allen <sla@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
On 10/4/18 3:13 PM, Tim Parenti wrote:
Gregorian calendar</a> with days containing 24 equal-length hours - numbered 00 through 23, except when clock transitions occur. + numbered 00 through 23 beginning with midnight, except when clock + transitions occur.
I'm afraid I'm not seeing what the "beginning with midnight" buys us. It already should be clear from the existing text that the hours in the day are numbered 00, 01, 02, ..., 23, so that 00 is the first hour of the calendar day and 23 is the last. Ethiopia time is out of our scope not so much because we can't represent current practice in many Addis Ababa businesses (we can), but because it's an independent feature that POSIX and/or tzdb is not set up to model. One can use so-called Ethiopian timekeeping in any timezone; should we set up an Ethiopian variant for every current tzdb identifier, for the benefit of Ethopians sojourning in other locations? And should we do something similar for Arab time, and other timekeeping practices? Surely not; it's better if these timekeeping practices are treated independently of tzdb proper and are handled by code and/or locales designed for them, as an axis independent of what tzdb supplies.
On Thu, 4 Oct 2018 at 21:15, Paul Eggert <eggert@cs.ucla.edu> wrote:
It already should be clear from the existing text that the hours in the day are numbered 00, 01, 02, ..., 23, so that 00 is the first hour of the calendar day and 23 is the last.
My argument is that that isn't clear, actually. That's the assumption we've all enjoyed, but it's evident that some prefer to count differently (for whatever reasons). One can use so-called Ethiopian timekeeping in any timezone;
should we set up an Ethiopian variant for every current tzdb identifier, for the benefit of Ethopians sojourning in other locations?
Not at all. Rather, by explicitly specifying that tz assumes hours are counted from "midnight", we emphasize that those sorts of adjustments are, in fact, outside our scope. I won't be bothered if it's left out, but I do think it helps to be clear here. -- Tim Parenti
Paul Eggert said:
Ethiopia time is out of our scope not so much because we can't represent current practice in many Addis Ababa businesses (we can), but because it's an independent feature that POSIX and/or tzdb is not set up to model. One can use so-called Ethiopian timekeeping in any timezone; should we set up an Ethiopian variant for every current tzdb identifier, for the benefit of Ethopians sojourning in other locations?
No, because that's not common practice in other countries. Everything I've read here says that a significant population in Ethiopia effectively runs their life on UTC-3 rather than the UTC+3 that people might expect. So I think it's reasonable to have that in the database. I see no difference between this and the decision to include Asia/Urumqi. -- Clive D.W. Feather | If you lie to the compiler, Email: clive@davros.org | it will get its revenge. Web: http://www.davros.org | - Henry Spencer Mobile: +44 7973 377646
On 10/11/18 7:28 AM, Clive D.W. Feather wrote:
that's not common practice in other countries.
Are you sure about that? Khalid recently reported here that the practice is currently common in Kenya and Somalia as well as in Ethiopia. Also, we have good evidence that it was common practice in Jiddah around 1970. I would expect that the practice has not entirely stopped there, and would not at all surprised to see it done in other countries as well. When Sudan had daylight saving time, my guess is that fans of the "my clock says 12:00 when European-style clocks say 06:00" practice also shifted their watches when DST started and stopped. To my mind this is more a localization preference than an independent time zone.
On Thu, 11 Oct 2018 at 10:49, Paul Eggert <eggert@cs.ucla.edu> wrote:
To my mind this is more a localization preference than an independent time zone.
…which, again, is why I suggested specifying that tz starts numbering the hours from midnight. Both counting practices can very much be considered to have days with hours numbered from 00 to 23, but only one starts at midnight. If indeed, anything else is considered localization, then that should probably be specified. On Thu, 11 Oct 2018 at 10:28, Clive D.W. Feather <clive@davros.org> wrote:
I see no difference between this and the decision to include Asia/Urumqi.
They count the hours in the same fashion as Asia/Shanghai, but unofficially observe a zone closer to their local solar time. There is certainly a gray area between these cases, but I think they're pretty clearly different. -- Tim Parenti
On Thu 2018-10-11T12:12:21-0400 Tim Parenti hath writ:
On Thu, 11 Oct 2018 at 10:49, Paul Eggert <eggert@cs.ucla.edu> wrote:
To my mind this is more a localization preference than an independent time zone.
…which, again, is why I suggested specifying that tz starts numbering the hours from midnight.
"midnight" has no meaning at South Pole station, nor on the ISS, and very little meaning at McMurdo other than how tired the supply crews from Christchurch are likely to be. At those places the hour 00 designates when the calendar day and date change. The concept of midnight is itself a localization of us temperate zone folks, and the word "midnight" has no place in tz other than in a footnote explaining the origin of the simplifications codified in the underlying tz model of time and date. -- Steve Allen <sla@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
On 2018-10-11 11:03, Steve Allen wrote:
On Thu 2018-10-11T12:12:21-0400 Tim Parenti hath writ:
On Thu, 11 Oct 2018 at 10:49, Paul Eggert wrote:
To my mind this is more a localization preference than an independent time zone. …which, again, is why I suggested specifying that tz starts numbering the hours from midnight. "midnight" has no meaning at South Pole station, nor on the ISS, and very little meaning at McMurdo other than how tired the supply crews from Christchurch are likely to be. At those places the hour 00 designates when the calendar day and date change. The concept of midnight is itself a localization of us temperate zone folks, and the word "midnight" has no place in tz other than in a footnote explaining the origin of the simplifications codified in the underlying tz model of time and date.
Might want to add some FAQ entries in the HTML docs around: - the working language of the list being English, as per ICANN Language Policy (can't find a similar IANA statement); - non-English names spelled as commonly used in English native language locales; - midnight and noon used to mean 0000 and 1200; - the charset encoding for file text data being US-ASCII; - UTF-8 used in some comments for clarity; - other statements to clarify practices; - links to entries in other languages making official statements about time zones or summer/daylight saving observance dates and times encouraged; and put descriptive English FAQ ids in HTML files at these statements (preferably para/div level, fallback to sentence/span level) so they may be referred to in replies, and used as a basis for applying moderation of excessive posts beating dead horses (of which many of us may have been guilty at times). -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada This email may be disturbing to some readers as it contains too much technical detail. Reader discretion is advised.
On Thu, 11 Oct 2018 at 13:04, Steve Allen <sla@ucolick.org> wrote:
On Thu 2018-10-11T12:12:21-0400 Tim Parenti hath writ:
On Thu, 11 Oct 2018 at 10:49, Paul Eggert <eggert@cs.ucla.edu> wrote:
To my mind this is more a localization preference than an independent time zone.
…which, again, is why I suggested specifying that tz starts numbering the hours from midnight.
"midnight" has no meaning at South Pole station, nor on the ISS, and very little meaning at McMurdo other than how tired the supply crews from Christchurch are likely to be.
That is a reasonable argument, though a bit imprecise. "Solar midnight" certainly has no meaning in those places, nor have I argued that it does.
At those places the hour 00 designates when the calendar day and date change.
The concept of midnight is itself a localization of us temperate zone folks,
This is the more salient point, I think. The folks in the places you mentioned may (or may not) bring their more temperate cultural notions of "midnight" with them to some extent, mainly with respect to communications with home bases, but that's more "imported" than anything truly localized to where they actually are. See also: Tourists to the Arctic amazed to "see the sun up at midnight" in the summer. It seems to be an absurd statement on its face, but it's not technically wrong, per se… at least, from their cultural frame-of-reference.
and the word "midnight" has no place in tz other than in a footnote explaining the origin of the simplifications codified in the underlying tz model of time and date.
I suppose I could argue that the patch I originally proposed in https://mm.icann.org/pipermail/tz/2018-October/026942.html *is* effectively such a footnote (one that aims to limit tz's scope) — but an alternative, more permissive, approach could certainly be taken to instead remove the other main mention of "midnight" where instead "start/end of calendar day" is more appropriate (likewise replacing "noon" with "midday"). Proposed alternate patch attached. The general concept of "midnight" in the wall-clock sense is, however, sufficiently commonly understood that it need not be eradicated from the (highly localized) commentary throughout. -- Tim Parenti
On Thu, Oct 11, 2018 at 10:49 PM Paul Eggert <eggert@cs.ucla.edu> wrote:
Are you sure about that? Khalid recently reported here that the practice is currently common in Kenya and Somalia as well as in Ethiopia. Also, we have good evidence that it was common practice in Jiddah around 1970. I would expect that the practice has not entirely stopped there, and would not at all surprised to see it done in other countries as well.
Last year I was talking to people who had visited Mt Athos, and I discovered something interesting. Mt Athos (in NE Greece) starts the calendar day at sunset. Hours are counted from sunset to sunset, so 0300 is when I go to bed, and 1300 is when I switch off the porch lights "sunset" is literal sunset; as the watches and clocks tick SI seconds, once every week or so, they are adjusted. They cannot really be in the UTC-0400 timezone, because they are also 13(?) days behind Greece. I am not sure if the calendar is Julian or Reformed Julian (or if anyone cares) They were not really into TZ-nuttery, but I did see some pictures on their cameras, which were timestamped Greek Time, but had local clocks in the background. So far so good? Then one of them pointed out that there was one(?) monastery which followed the same system, but counted days from sunrise. He did not know if they were ahead or behind in their day count (and he couldn't believe anyone could care). Cellphones are not rare on the island, and they (as well as the ferry schedule) seems to be in Greek civil time. This issue has been raised before, please see: https://mm.icann.org/pipermail/tz/2007-April/014310.html PS: Mt Athos' status was carefully negotiated when Greece joined the EEC/EU, it is exempt from the "free movement of people"/Schengen Area. EU (and Greek) citizens need a visa to enter. No women are permitted, not even Govt officials. PPS: The good news is, we will not have a case where the time zone changes because the President has signed a decree overnight; the Monasteries hold individual charters over a thousand years old, and will accept (perhaps) only the authority of an Emperor confirmed by the Senate of the Roman Empire. I welcome a discussion on how leap seconds are implemented on Mt Athos. -- Sanjeev Gupta +65 98551208 http://www.linkedin.com/in/ghane
On Oct 11, 2018, at 21:21, Sanjeev Gupta <ghane0@gmail.com> wrote:
[The monasteries on Mount Athos] will accept (perhaps) only the authority of an Emperor confirmed by the Senate of the Roman Empire.
Based on past experience —e.g. Emperor Julian (ca. 360-361 AD) — I’d have my doubts even of that. Cheers! |----------------------------------------------------------------------| | Frederick F. Gleason, Jr. | Chief Developer | | | Paravel Systems | |----------------------------------------------------------------------| | Impossible, adj.: | | (1) I wouldn't like it and when it happens I won't approve; | | (2) I can't be bothered; (3) God can't be bothered. Meaning (3) may | | perhaps be valid but the others are 101% whaledreck. | | -- Chad C. Mulligan | | "The Hipcrime Vocab" | |----------------------------------------------------------------------|
Formally speaking, Ethiopia is already "supported" by tz insofar as its offset of UTC+3 is recorded and referenced as Africa/Addis_Ababa (which is a link to Africa/Nairobi). But, even if we ignore the differences between atomic and solar time — it sounds like both see some use, depending on the precision required — the unique way of naming the hours is a different problem entirely. Much like we're seeing with current discussion re: fallback transitions in mid-20th-century Japan, the tz database isn't really concerned so much with what the hours are *called* as how they are *counted*… Or at least, that's the best I can say in words; it's a wiggly distinction, to be sure, and edge cases like this do exist. All tz does, though, given a timestamp, is to convert that into some local reckoning by spitting out the elements of a Gregorian date and a time-of-day according to a standard 24-hour clock, counting from 00:00:00. Obviously, that intuition gets hairy at various time discontinuities (DST and leap seconds are both examples, but are not handled analogously). However, convention has been established by some decades of global precedent and practice. While it would be technically possible to implement different models for this, it would likely require some major code changes. In most of the world, tz's output maps pretty cleanly to how time is reckoned by everyday folk: e.g., right now, we're I'm at, it's 17:00. In some parts, there may be a conventional mapping to other customary terminology; e.g., it's 5:00pm. This 12-hour system maps what tz calls "hour 0" to the concept of "12am", and so on through "hour 23" being called "11pm". And while it is widely supported in most systems because it is a relatively simple transformation and its use is prevalent throughout the world (though a historical dose of US-centrism likely helped, too), it has nothing to do with tz's outputs themselves, and more to do with how those results are formatted. In many parts of Europe and Asia, 17:00 could be used directly and would be well-understood. This is analogous to mapping dates to different calendar systems: tz uses the proleptic Gregorian calendar and will tell me, in its structured data format, that today is 2018-09-12, and while that's directly useful to telling me it's "12 September 2018" in the calendar I use, if I wanted to know that it was "3 Tishrei 5779" in the Hebrew calendar or "1 Muharram 1440" in the Islamic calendar, I would need to perform a calculation, and that calculation is outside the scope of tz. The gut reaction of some might be to paper over Ethiopia's unique system by picking some timezone 6 hours east or west (UTC–3 or UTC+9, for example), but it raises additional questions: When should the date change over, near dusk, near dawn — or still at "midnight", which is to say "6 o'clock"? Does traditional Ethiopian timekeeping have the same notion of "am" or "pm", and is that even accurate terminology, if we were to translate that notion into English? Does Ethiopian practice match the Western convention which starts the "am" and "pm" periods with the hour called "12" and not with "1"? I'd be inclined to say that the "correct" way to support the traditional Ethiopian timescale would be for tz to still output Ethiopian time in the standardized way it already does, and for applications and operating systems to then understand that "17:00" in the standard system doesn't mean "5 o'clock", but rather should be displayed to be understood as "11 o'clock". It could be another localization option, just like alternate calendars are today. Unfortunately, unlike the various calendar systems, which enjoy a decent amount of support, Ethiopia is (to our knowledge) unique in this regard. But a decent thought experiment would be to consider how tz and localization projects like CLDR would have managed with Decimal Time <https://en.wikipedia.org/wiki/Decimal_time> in the French Revolution. That's a *very* different way of counting hours; at least Ethiopia's is relatively similar to things we already support. Depending on how seriously others take, say, the prospect of supporting other timescales entirely (TAI or GPS, perhaps, but maybe as far-reaching as Mars time) becoming important in the future, the place for that sort of support might land in that project, be it tz or otherwise. But for now, I think it's more of a localization issue than a timekeeping one: They're using different names for the same underlying thing. -- Tim Parenti On Wed, 12 Sep 2018 at 16:06, <Paul.Koning@dell.com> wrote:
On Sep 12, 2018, at 3:58 PM, Steve Allen <sla@ucolick.org> wrote:
On Tue 2018-09-11T22:23:01-0700 Paul Eggert hath writ:
I'm afraid not, as it's based on solar time.
The article gives the impression that it's not really solar because an hour of imprecision is culturally irrelevant, so it's really just 6 hours different from what a cell phone says. But even with that simplicity I don't think that tz should implement something without a much more authoritative and clear source for when the Ethiopian day begins.
-- Steve Allen <sla@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
That brings up an interesting question.
What does the TZ database mean "local time" to be? Time in its common representation where zero is midnight and 12 o'clock is noon? Or is it meant to account also for local conventions that zero is some point in the day different from midnight?
If the former, then this issue is out of scope. If the latter, then it suggests there might be two Ethiopia zones, one for "midnight origin" (the one we have now) and one for "local convention" which combines the offsets from latitude, and the offset from the different convention of what the starting point is.
paul
On 2018-09-12 15:00, Tim Parenti wrote:
But for now, I think it's more of a localization issue than a timekeeping one: They're using different names for the same underlying thing.
Maybe theory could say something about supporting global standard time zone offsets from UTC based on longitude, plus DST rules, and that local offsets from standard time zone offsets are a localization issue, as is e.g. military time 01.00-24.59 and Japanese times > 24.00? -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada This email may be disturbing to some readers as it contains too much technical detail. Reader discretion is advised.
Brian Inglis wrote:
Maybe theory could say something about supporting global standard time zone offsets from UTC based on longitude, plus DST rules, and that local offsets from standard time zone offsets are a localization issue, as is e.g. military time 01.00-24.59 and Japanese times > 24.00?
I gave that a shot in the attached proposed patch.
On Fri 2018-09-14T18:51:12-0700 Paul Eggert hath writ:
I gave that a shot in the attached proposed patch.
+ And even today, some local practices diverge from the Gregorian + calendar with 24-hour days. These divergences range from + relatively minor, such as Japanese bars giving times like "24:30" for the + wee hours of the morning, to more-significant differences such as <a + href="https://www.pri.org/stories/2015-01-30/if-you-have-meeting-ethiopia-you-better-double-check-time">the + east African practice of starting the day at dawn</a>, renumbering + the Western 06:00 to be 12:00. These practices are largely outside + the scope of the <code><abbr>tz</abbr></code> code and data, which + provide only limited support for date and time localization + such as that required by POSIX.
This does not explicitly address the original question that prompted the text. It appears that the common parlance in several equatorial east African regions is to have hour 0 and the change of date at 06:00 according to cell phones that are showing UTC+3. Therefore people who wish their devices to give common time (and date) rather than cell phone time (and date) have already been and can continue to be able to achieve this by setting a device to use UTC-3. The flaw in this scheme is that device vendors may not have allowed that as one of the choices. Is there objection to enhancing the patch text to mention this explicitly? -- Steve Allen <sla@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
On 2018-09-15 12:42, Paul Eggert wrote:
Steve Allen wrote:
Is there objection to enhancing the patch text to mention this explicitly?
No, that was an oversight. Thanks for pointing it out. I installed the attached, which I hope addresses this.
May want to emphasize that this approach only works/should be used if both zones observe year round standard time with no DST as in equatorial zones. -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada This email may be disturbing to some readers as it contains too much technical detail. Reader discretion is advised.
On 10/11/18 7:17 AM, Brian Inglis wrote:
May want to emphasize that this approach only works/should be used if both zones observe year round standard time with no DST as in equatorial zones.
It can work to some extent even if DST is being observed. For the DST rules for Sudan 1972-1985, for example, TZ='<-04>4<-03>,M4.5.0/-6,J288/-6' should work on tz-compatible platforms. Admittedly this sort of thing is not for the fainthearted, nor will this particular example work with common cellphone UIs or on strict POSIX platforms. It's probably not worth going into all this in theory.html, though, so I installed the first attached proposed patch. While looking into this I discovered that zic.c does not allow negative times in Rule lines, contrary to the documentation since 2018a. Negative times would be needed to support Ethiopian-style timekeeping in zones where the European-time transitions are betwee 00:00 and 06:00, as in the case in Sudan 1972-1985, where the zic input might have looked like this: Rule Sudan-Ethiopian-style 1972 max - Oct 15 -6:00 0 - Rule Sudan-Ethiopian-style 1972 max - Apr lastSun -6:00 1:00 - Zone Africa/Khartoum-Ethiopian-style 2:10:08 - LMT 1931 -4:00 Sudan-Ethiopian-style -04/-03 I fixed this by installing the second attached proposed patch.
participants (17)
-
admin＠afocha.com -
Arthur David Olson -
Brian Inglis -
Clive D.W. Feather -
David Patte -
Fred Gleason -
Guy Harris -
Khalid H. Duri -
Patrice Scattolin -
Paul Eggert -
Paul.Koning＠dell.com -
Phake Nick -
Philip Paeps -
Sanjeev Gupta -
Steve Allen -
Steven R. Loomis -
Tim Parenti