I don't know if it would serve your purposes but there is a list of Tz time zones at Wikipedia if you're not aware of it: List of tz database time zones https://en.wikipedia.org/wiki/List_of_tz_database_time_zones It would be a simple matter to print that list. I'm not sure it's comprehensive, up to date, or who maintains it, but I've not seen any blatant errors and find it usful as a general guide. -Brooks On 2023-10-20 1:27 PM, Alexandre Petrescu via tz wrote:

Le 15/10/2023 à 02:28, natyaveda via tz a écrit :

...

Hey, are you aware of any printable or hard copy (paper) publications of your Time-Zone database in a complete or semi-complete form?

I am looking to obtain approximately the same.

The full database might be too much to print and read. But a concise form of it, on an A4 or letter sized paper, might be useful. It should be updateable easily, every few months or so. It should contain the capitals and major cities worldwide. Should not contain the past history info. Should list the names in alphabetical order, and with several spellings (local spelling first). It should tell the date of the next few DST changes. Should be printed in a large font. Should be used when Internet is not available.

Other than that hard copy, I am also interested to be notified by email about the single next DST change that will happen at a site worldwide (not only at my place). For example, I think now the next DST change (no DST) is going to happen in Europe in November, but not sure whether there are others before that.

Alex

...

Perhaps this has been produced by someone in the astrology community?

I'm basically looking to see if its possible to get the rights to include parts of such a publication in a publication of my own. I doubt one exists that includes all the info for every city in the world in a single publication, but I'm looking to see if it does and how large it might be.

What I have in mind is something that lists information pretty much exactly as its presented in the tables for the "Detailed time zone and clock changes" available on timeanddate.com (minus everything outside the tables):

https://www.timeanddate.com/time/zone/canada/vancouver <https://www.timeanddate.com/time/zone/canada/vancouver>

Thanks for any info you can provide!

-James Foyle

On 2023-10-20 3:19 PM, Tim Parenti via tz wrote:

On Fri, 20 Oct 2023 at 13:27, Alexandre Petrescu via tz <tz@iana.org <mailto:tz@iana.org>> wrote:

I am also interested to be notified by email about the single next DST change that will happen at a site worldwide (not only at my place). For example, I think now the next DST change (no DST) is going to happen in Europe in November, but not sure whether there are others before that.

timeanddate.com <http://timeanddate.com> publishes detailed listings of all their known DST changes for each half-year, ordered by wall-clock date-time: https://www.timeanddate.com/time/dst/2023b.html https://www.timeanddate.com/time/dst/2024a.html

-- Tim Parenti

Ah! Very nice! Time and Date does a very good job. I use it all the time to help me decipher the intricacies of the TzDb source files. Thanks. -Brooks

On 2023-10-20 11:27, Alexandre Petrescu via tz wrote:

Le 15/10/2023 à 02:28, natyaveda via tz a écrit :

...

Hey, are you aware of any printable or hard copy (paper) publications of your Time-Zone database in a complete or semi-complete form? Perhaps this has been produced by someone in the astrology community? I'm basically looking to see if its possible to get the rights to include parts of such a publication in a publication of my own.  I doubt one exists that includes all the info for every city in the world in a single publication, but I'm looking to see if it does and how large it might be. What I have in mind is something that lists information pretty much exactly as its presented in the tables for the "Detailed time zone and clock changes" available on timeanddate.com (minus everything outside the tables): <https://www.timeanddate.com/time/zone/canada/vancouver>

I am looking to obtain approximately the same. The full database might be too much to print and read. But a concise form of it, on an A4 or letter sized paper, might be useful. It should be updateable easily, every few months or so. It should contain the capitals and major cities worldwide. Should not contain the past history info. Should list the names in alphabetical order, and with several spellings (local spelling first). It should tell the date of the next few DST changes. Should be printed in a large font. Should be used when Internet is not available. > Other than that hard copy, I am also interested to be notified by email about the single next DST change that will happen at a site worldwide (not only at my place). For example, I think now the next DST change (no DST) is going to happen in Europe in November, but not sure whether there are others before that. I have defined a zdump alias for interactive use (below) which searches backwards for the first transition in the given zone (or local time) from this year, displaying them up to the start of next year (whose data is not included in any output), which you may be able to adapt by iterating thru all zones of interest, which could just be symlinks to zoneinfo in some directory as in the examples at the top of the shell commands and output.

And seriously *hardcopy*, in this century (other than for tax backups, which are still based on Roman technology)?! At least generate markdown or html which can be displayed locally in a browser, or converted to a digital document using pandoc, htmldoc, or similar. Then you can run this generation process whenever a new tz release is detected automatically, so it is always up to date. # zdump interesting zones using alias or script then post-process $ ln -st ./interested/ /usr/share/zoneinfo/Europe/Brussels ... # symlink zones $ for tz in ./interested/*; do zdump $tz; done | process # output zones $ which zdump # interactive alias zdump () { local z=${@:-${TZ:-/etc/localtime}} y=$(date +%Y); local e=$(($y+1)) b p l t; for b in $y 1970 1900 1752; do range=-Vc$b,$e; p=$(command /usr/bin/zdump $range $z); [ -n "$p" ] && break; done; l=${p##*' '}; t=${l##*[012][0-9]:[0-5][0-9]:[0-6][0-9] }; b=${t:0:4}; if [ -n "$b" ]; then range=-Vc$b,$e; [ $b -lt $y ] && p=$(command /usr/bin/zdump $range $z); else range=''; p=$(command /usr/bin/zdump $range $z); fi; [ -n "$range" ] && echo zdump $range $z; echo "$p" } # zdump alias example outputs $ zdump Europe/Brussels zdump -Vc2023,2024 Europe/Brussels Europe/Brussels Sun Mar 26 00:59:59 2023 UT = Sun Mar 26 01:59:59 2023 CET isdst=0 gmtoff=3600 Europe/Brussels Sun Mar 26 01:00:00 2023 UT = Sun Mar 26 03:00:00 2023 CEST isdst=1 gmtoff=7200 Europe/Brussels Sun Oct 29 00:59:59 2023 UT = Sun Oct 29 02:59:59 2023 CEST isdst=1 gmtoff=7200 Europe/Brussels Sun Oct 29 01:00:00 2023 UT = Sun Oct 29 02:00:00 2023 CET isdst=0 gmtoff=3600 $ zdump zdump -Vc2023,2024 America/Edmonton America/Edmonton Sun Mar 12 08:59:59 2023 UT = Sun Mar 12 01:59:59 2023 MST isdst=0 gmtoff=-25200 America/Edmonton Sun Mar 12 09:00:00 2023 UT = Sun Mar 12 03:00:00 2023 MDT isdst=1 gmtoff=-21600 America/Edmonton Sun Nov 5 07:59:59 2023 UT = Sun Nov 5 01:59:59 2023 MDT isdst=1 gmtoff=-21600 America/Edmonton Sun Nov 5 08:00:00 2023 UT = Sun Nov 5 01:00:00 2023 MST isdst=0 gmtoff=-25200 $ zdump America/Regina zdump -Vc1960,2024 America/Regina America/Regina Sun Apr 24 08:59:59 1960 UT = Sun Apr 24 01:59:59 1960 MST isdst=0 gmtoff=-25200 America/Regina Sun Apr 24 09:00:00 1960 UT = Sun Apr 24 03:00:00 1960 CST isdst=0 gmtoff=-21600 -- Take care. Thanks, Brian Inglis Calgary, Alberta, Canada La perfection est atteinte Perfection is achieved non pas lorsqu'il n'y a plus rien à ajouter not when there is no more to add mais lorsqu'il n'y a plus rien à retirer but when there is no more to cut -- Antoine de Saint-Exupéry

Alexandre Petrescu wrote:

But the names of the timezones are a much more difficult matter. The names of cities, countries or regions are so difficult to identify. It comes down to manually grepping 'city' to identify the continent file, and then vi to search for the Zone. The principal difficulty in this is to write down 'city' in the right way; and that way is not necessarily the correct way of writing 'city'. There is an additional difficulty in identifying _which_ city is representative for a particular place whose time and DST I need, but that is a geography problem.

GeoNames (https://www.geonames.org/) is your friend. It lists millions of places, each with an associated tzid, and most with a variety of localized names.

Additionally, one might not have a usable computer to store that data to. So all one could do is to rely on printed tables of most recent timezone data that was available when Internet was last available.

Well, sure, if you can’t even assume the existence of a computer, then school’s pretty much out. -- Doug Ewell, CC, ALB | Lakewood, CO, US | ewellic.org

Alexandre Petrescu wrote:

Should be used when Internet is not available.

I would guess that very few systems depend on Internet connectivity to access the current tz database. Storing it locally seems much more sensible. -- Doug Ewell, CC, ALB | Lakewood, CO, US | ewellic.org

Le 20/10/2023 à 22:40, Doug Ewell a écrit :

Alexandre Petrescu wrote:

...

Should be used when Internet is not available. I would guess that very few systems depend on Internet connectivity to access the current tz database. Storing it locally seems much more sensible.

Sure.  It should come from the Internet and stored locally. One would like to store it locally once one sees an email declaration from a gov't on this list, and not necessarily fast continuous updates. But in that, one assumes Internet access is readily available when one needs it.  This might not be the case.  One might need to know now the date of some place, without having Internet access. Additionally, one might not have a usable computer to store that data to.   So all one could do is to rely on printed tables of most recent timezone data that was available when Internet was last available. Alex

-- Doug Ewell, CC, ALB | Lakewood, CO, US | ewellic.org

On 2023-10-20 15:32, Guy Harris via tz wrote:

On Oct 20, 2023, at 2:04 PM, Alexandre Petrescu via tz wrote:

...

Le 20/10/2023 à 22:40, Doug Ewell a écrit :

...

Alexandre Petrescu wrote:

...

Should be used when Internet is not available. I would guess that very few systems depend on Internet connectivity to access the current tz database. Storing it locally seems much more sensible. Sure. It should come from the Internet and stored locally. On my system, running macOS, the tzdb originally came pre-installed. Both operating system updates and tzdb data updates do, indeed, come from the Internet, and are stored locally. One would like to store it locally once one sees an email declaration from a gov't on this list, and not necessarily fast continuous updates. The tzdb isn't continuously updated. New versions are produced as necessary; the tzdb home page: https://www.iana.org/time-zones indicated that the current official is 2023c, released 2023-03-28, so the last update was almost 7 months ago.

Releases are dated and labelled at: https://github.com/eggert/tz/tags

...

But in that, one assumes Internet access is readily available when one needs it. "When one needs it" is "when the tzdb is updated"; that, as noted, hasn't happened for almost 7 months. As there aren't continuous updates to the tzdb, continuous Internet access is not necessary. This might not be the case. One might need to know now the date of some place, without having Internet access. <turns Wi-Fi off to completely remove Internet access> <goes to a Terminal.app window> <types TZ=Europe/Berlin date> Fri Oct 20 23:13:58 CEST 2023 So, yes, indeed, at least if you know the tzid for the tzdb region containing that place, you can know the date and time at that place without having Internet access. With additional local data and software to let you look up the place and get the tzid, it would be even easier, but "place -> tzid" is not part of the scope of the tzdb. The Clock app on my Mac, running Ventura, has a "World Clock" pane that lets me select a city, from a list that includes more than just the cities used to form tzids (but that doesn't, for example, include Christchurch, New Zealand, for some reason, even though it includes the city in which I live). It works even with my Internet access turned off. The same applies to the Clock app on my iPhone, even with both wi-fi and cellular data turned off. The same may apply to third-party apps for both platforms, as well as built-in and third-party apps on Android and various clock apps for other platforms. Additionally, one might not have a usable computer to store that data to. That's a different issue. If you don't have a usable computer (where "computer" includes "smartphone", as per the above), you probably lack Internet access, and also probably lack anything that could *use* the data, so, yes, a printed table would be necessary. So all one could do is to rely on printed tables of most recent timezone data that was available when Internet was last available. As per my other mail, what you would want is a printed table of *compiled versions of* recent timezone data. The tzdb does *not* consist of a list of time transitions, it consists of a list of rule and zone information from which the transitions can be calculated. The zic command compiles those into binary lists of transitions, and, as has been noted here, current versions of the zdump command can dump out those lists in a somewhat human-readable form.

If you don't have a computer, why would you need timezone data? A watch is fine. Until you get involved with computers, and time, projects like this, and NTP, and GPS receivers, computers to process their data, tell you the precise time, keep their stats, calculate their RMS, standard, Allen, and Hadamard deviations to the nearest [munpf]s, depending on your background, and the offsets from that in every zone in the world. Aargh! ;^> -- Take care. Thanks, Brian Inglis Calgary, Alberta, Canada La perfection est atteinte Perfection is achieved non pas lorsqu'il n'y a plus rien à ajouter not when there is no more to add mais lorsqu'il n'y a plus rien à retirer but when there is no more to cut -- Antoine de Saint-Exupéry

Le 22/10/2023 à 12:25, Alexandre Petrescu via tz a écrit :

Le 22/10/2023 à 02:37, Brian Inglis via tz a écrit :

...

On 2023-10-20 15:32, Guy Harris via tz wrote:

...

On Oct 20, 2023, at 2:04 PM, Alexandre Petrescu via tz wrote:

...

Le 20/10/2023 à 22:40, Doug Ewell a écrit :

...

Alexandre Petrescu wrote:

...

Should be used when Internet is not available. I would guess that very few systems depend on Internet connectivity to access the current tz database. Storing it locally seems much more sensible. Sure. It should come from the Internet and stored locally. On my system, running macOS, the tzdb originally came pre-installed.  Both operating system updates and tzdb data updates do, indeed, come from the Internet, and are stored locally. One would like to store it locally once one sees an email declaration from a gov't on this list, and not necessarily fast continuous updates. The tzdb isn't continuously updated.  New versions are produced as necessary; the tzdb home page:     https://www.iana.org/time-zones indicated that the current official is 2023c, released 2023-03-28, so the last update was almost 7 months ago.

Releases are dated and labelled at:

    https://github.com/eggert/tz/tags

...

...

But in that, one assumes Internet access is readily available when one needs it. "When one needs it" is "when the tzdb is updated"; that, as noted, hasn't happened for almost 7 months.  As there aren't continuous updates to the tzdb, continuous Internet access is not necessary. This might not be the case.  One might need to know now the date of some place, without having Internet access.     <turns Wi-Fi off to completely remove Internet access>     <goes to a Terminal.app window>     <types TZ=Europe/Berlin date>     Fri Oct 20 23:13:58 CEST 2023 So, yes, indeed, at least if you know the tzid for the tzdb region containing that place, you can know the date and time at that place without having Internet access. With additional local data and software to let you look up the place and get the tzid, it would be even easier, but "place -> tzid" is not part of the scope of the tzdb. The Clock app on my Mac, running Ventura, has a "World Clock" pane that lets me select a city, from a list that includes more than just the cities used to form tzids (but that doesn't, for example, include Christchurch, New Zealand, for some reason, even though it includes the city in which I live).  It works even with my Internet access turned off.  The same applies to the Clock app on my iPhone, even with both wi-fi and cellular data turned off. The same may apply to third-party apps for both platforms, as well as built-in and third-party apps on Android and various clock apps for other platforms. Additionally, one might not have a usable computer to store that data to. That's a different issue. If you don't have a usable computer (where "computer" includes "smartphone", as per the above), you probably lack Internet access, and also probably lack anything that could *use* the data, so, yes, a printed table would be necessary. So all one could do is to rely on printed tables of most recent timezone data that was available when Internet was last available. As per my other mail, what you would want is a printed table of *compiled versions of* recent timezone data.  The tzdb does *not* consist of a list of time transitions, it consists of a list of rule and zone information from which the transitions can be calculated.  The zic command compiles those into binary lists of transitions, and, as has been noted here, current versions of the zdump command can dump out those lists in a somewhat human-readable form.

If you don't have a computer, why would you need timezone data? A watch is fine.

Smartwatches need recharge.

Simpler electronic watches that keep timezones hard-code the DST changes, and thus need regular update of the DST date changes after manufacturing.

Watches receiving time signals (DCF in central Europe) are subject to security attacks (I suppose), and, anyways, see the DST changes only of that particular region.  They also depend on the signal visibility wherever that is used (long waves hardly penetrate in many places where people live).

...

Until you get involved with computers, and time, projects like this,

This is a great project and I am happy how it works, where it is hosted, and other aspects.

However, people communicate dates and times by many other long-range communication media than the Internet.  One sees dates and times communicated on TV, on the phone, on ham radio and many other non-Internet media.  These work ok when Internet access is not working.

Correctly correlating events, especially during delicate moments such as DST regular changes but also during the ever more migrations away from it, is a help.

I meant to say: DST regular changes, migrations away from DST changes, _and_ timezone outright changes (move a region from a timezone to another).  These timezone changes seem regular in recent years.  I think they are even accelerating.  It is important to have the precise current status at hand even if Internet access is not available. When I read the comments about the history, in the tz database, it feels like there were so many changes only around the moment they introduced GMT, and then maybe during world wars. It does not seem to stabilize - independent of the arrival of Internet and computers.  On the contrary, it might seem as the Internet and computers actually help to accommodate more and more changes in timezones. Alex

Many computers still bug during these delicate events.  Microsoft outlook was the most recent I heard of in the public, but it is not the only one.

...

and NTP, and GPS receivers, computers to process their data, tell you the precise time, keep their stats, calculate their RMS, standard, Allen, and Hadamard deviations to the nearest [munpf]s, depending on your background, and the offsets from that in every zone in the world. Aargh! ;^>

Computers are great, but they need be backed up by some non-computer, in the sense of trusting but verifying.

(hadamard deviation... I'll have to look that up).

Alex