"Sascha Wildner" <saw@online.de> wrote: |On Thu, 24 May 2012 12:11:32 +0200, Tobias Conradi |<tobias.conradi@gmail.com> wrote: | |> was: Re: [tz] Propose new zone for Crozet Islands | |How about just working out all your little "proposals" privately and |posting a _patch_ to tzdata* like it is good practice? Yes. |I for one will subscribe to the announce list because I'm really getting |tired of your seemingly endless, annoying dribble. And i *don't* wanna do that, because there were really interesting topics once in a while, and things good to learn about, and that's what it's about for me. And from what i know his last posts really revealed fuzzy stuff that could be improved (or de-improved). Here i'm with your first sentiment, though. I in turn got response from the German Navy, the second. Thanks to Herrn Kapitänleutnant Daub (Mr. Lieutenant Daub) and Herrn Oberstabsbootsmann Jürgen Haak (Mr. Master Chief Petty Officer Juergen Haak). For the German Navy: Wir können Ihnen hier lediglich Informationen darüber geben, wie die Schiffe/Boote der Marine es in der Praxis mit den Zeitzonen handhaben. So fahren diese in der Regel in den jeweiligen Zonenzeiten mit Erreichen des entsprechenden Gebiets. Sonderregelungen (z. B. während Manövern/Übungen) sind möglich und werden vorab bekanntgegeben. So the germans basically agree with the post from the former Navy member ("normally local area time is used", "special arrangements are possible and will be gazetted") if i recall correctly. It was the "we have the better Kung-Fu" mail. (And i was in doubt because whoever has the better Kung-Fu actually didn't really understand what Kung-Fu is about, but maybe it's simply a good job. Sorry.) Möglicherweise kann Ihnen aber das Bundesamt für Seeschifffahrt und Hydrographie bezüglich der rechtlichen Regelungen Auskunft geben bzw. zuständige Ansprechpartner benennen. Yes, i didn't have had a clue and should of course have asked the Federal Agency instead! The question is - should i really do that? Does it *really* matter what timezone a ship uses regarding to the timezone database? Maybe i have mislead myself. On the other hand i'll send another mail if some international law actually exists (which is what i have asked for), for completeness?! Thanks.

"Tim Thornton" <tt@smartcomsoftware.com> wrote: |Maritime time zones are well defined - basically every 15 degrees but with |the odd wiggle in them - see |http://www.usno.navy.mil/USNO/astronomical-applications/images_aa/TimeZoneMa |p0210.jpg Thanks for the pointer. My question to the German Navy was more like Es geht im speziellen um das Umfeld um (Territorialgewässer) und die Landungen auf unbewohnten Eilanden, für die aber ein gültiger ISO 3166 [6,7] Länderkode vorliegt (wie also z. B. DE und DEU für Deutschland). Roughly a question about "territorial waters and landings on uninhabited islands, especially those for which a valid ISO 3166 country code exists". Was interessant wäre, ist, ob es (international) gültige rechtliche Regelungen gibt, nach denen in solchen Situationen verfahren wird. I'm asking wether international laws exist which handle this situation (i.e., which are to be obeyed). |They are identified by a letter, as shown in the above diagram. |They were created in the 1920s and I think are virtually unchanged since |then. |Note that the nautical date line is different from the international date |line. |Also, it uses GMT (i.e. UT1, not UTC) - I'm not sure if the tz database can |cope with this, or if the difference (< 1 second) is relevant for most tz |users. Well i hope the german navy gets that right - as far as i know the new generation of ships (ordered about ten years ago say) uses Microsoft software even on the bridge. It's quite fascinating to read about the history of timezones. Hundred years ago different times were in use just a few kilometres from here! I don't think humans changed that much, but the technology did. And now i've looked into http://en.wikipedia.org/wiki/Universal_Time and http://en.wikipedia.org/wiki/Nautical_time. The latter states A ship is required to adopt the standard time of a country when it is in its territorial waters, but must revert to nautical time as soon as it leaves territorial waters. But no references, nowhere. |So they could be included in the TZ database if people feel this is good - |it would make the database more complete. Perhaps in a separate file, as |they are not associated with any of the continents? Aquarius time, maybe. I yet see no cities under water and such, but the dutch, for example, already plan and build houses that swim; they are in trouble pretty soon - but have the technology to face it. But i agree that landings on uninhabited islands are not really related to this timezone database. |Tim --steffen |Smartcom Software Ltd |Portsmouth Technopole |Kingston Crescent |Portsmouth PO2 8FA |United Kingdom | |www.smartcomsoftware.com | |Smartcom Software is a limited company registered in England and Wales, |registered number 05641521. | | |-----Original Message----- |From: tz-bounces@iana.org [mailto:tz-bounces@iana.org] On Behalf Of Steffen |Daode Nurpmeso |Sent: 24 May 2012 13:52 |To: Sascha Wildner |Cc: tz@iana.org |Subject: Re: [tz] time zone abbreviations - uniqueness and meaning | |"Sascha Wildner" <saw@online.de> wrote: | | |On Thu, 24 May 2012 12:11:32 +0200, Tobias Conradi ||<tobias.conradi@gmail.com> wrote: | | | |> was: Re: [tz] Propose new zone for Crozet Islands | |How about just |working out all your little "proposals" privately and |posting a _patch_ to |tzdata* like it is good practice? | |Yes. | | |I for one will subscribe to the announce list because I'm really getting ||tired of your seemingly endless, annoying dribble. | |And i *don't* wanna do that, because there were really interesting topics |once in a while, and things good to learn about, and that's what it's about |for me. | |And from what i know his last posts really revealed fuzzy stuff that could |be improved (or de-improved). Here i'm with your first sentiment, though. | | |I in turn got response from the German Navy, the second. |Thanks to Herrn Kapitänleutnant Daub (Mr. Lieutenant Daub) and Herrn |Oberstabsbootsmann Jürgen Haak (Mr. Master Chief Petty Officer Juergen |Haak). |For the German Navy: | | Wir können Ihnen hier lediglich Informationen darüber geben, wie | die Schiffe/Boote der Marine es in der Praxis mit den Zeitzonen | handhaben. So fahren diese in der Regel in den jeweiligen | Zonenzeiten mit Erreichen des entsprechenden Gebiets. | Sonderregelungen (z. B. während Manövern/Übungen) sind möglich | und werden vorab bekanntgegeben. | |So the germans basically agree with the post from the former Navy member |("normally local area time is used", "special arrangements are possible and |will be gazetted") if i recall correctly. |It was the "we have the better Kung-Fu" mail. (And i was in doubt because |whoever has the better Kung-Fu actually didn't really understand what |Kung-Fu is about, but maybe it's simply a good job. Sorry.) | | Möglicherweise kann Ihnen aber das Bundesamt für Seeschifffahrt | und Hydrographie bezüglich der rechtlichen Regelungen Auskunft | geben bzw. zuständige Ansprechpartner benennen. | |Yes, i didn't have had a clue and should of course have asked the Federal |Agency instead! |The question is - should i really do that? Does it *really* matter what |timezone a ship uses regarding to the timezone database? Maybe i have |mislead myself. On the other hand i'll send another mail if some |international law actually exists (which is what i have asked for), for |completeness?! |Thanks. | |

Hi Zefram, Thanks for that useful information. Actually marine time zones DO use UT1, because of the link between time and astro (or celestial) navigation. The sign difference is because the conference that set up the nautical time zones intentionally adopted this sign convention, which is unfortunately the opposite of that used for terrestrial time zones - look up in any nautical publication that has time zones, e.g. Admiralty Tide Tables or Admiralty List of Radio Signals, and you will see this specifically maritime sign convention used. I don't know which came first, the maritime or the time zone sign convention, but it is confusing. Tim Smartcom Software Ltd Portsmouth Technopole Kingston Crescent Portsmouth PO2 8FA United Kingdom www.smartcomsoftware.com Smartcom Software is a limited company registered in England and Wales, registered number 05641521. -----Original Message----- From: Zefram [mailto:zefram@fysh.org] Sent: 24 May 2012 16:23 To: Tim Thornton Cc: tz@iana.org Subject: Re: [tz] Maritime time zones Tim Thornton wrote:

Also, it uses GMT (i.e. UT1, not UTC) - I'm not sure if the tz database can cope with this,

The tz database is effectively silent on which flavour of UT is the basis for timezone offsets. Its offsets are not meaningful at a subsecond level. The maritime timezone system also long predates the need to distinguish flavours of UT, and I'd be surprised if it really is specified to use UT1 rather than UTC. So, in any case, the tz database can represent the maritime timezones just fine.

So they could be included in the TZ database

They are. See the zones Etc/GMT-12 to Etc/GMT+12, in the "etcetera" source file. (There are also a couple more fixed-offset zones that are outside the maritime system.) Beware that the sign in the zone's name is the opposite of the offset's sign, due to an historical confusion with the negated-sign aspect of POSIX TZ format. The initialisms of these zones match the names, and do not use the maritime letters. A single-letter initialism would be a problem, because the POSIX TZ format requires initialisms to be at least three characters, so a time-using program might reasonably expect the initialism to be at least three characters. The Theory file has a note about sticking to this. However, aside from the historical fact of them already being in the database, fixed-offset zones are generally out of scope for the tz database. In general if you want a fixed offset, and in particular if you want a fixed offset with an initialism based on the nautical letters, I suggest that you use an actual POSIX TZ value. For example: TZ=seaA-1 TZ=seaM-12 TZ=seaN1 TZ=seaY12 TZ=seaZ0 -zefram

On 24 May 2012 17:18, Alan Mintz <Alan_Mintz+TZ_IANA@earthlink.net> wrote:

Note that the nautical date line is different from the international date

...

line.

Where (as of 2010)?

The "nautical date line," used when not in territorial waters, is the 180th meridian by convention, which splits the 15-degree range from 172.5°E to 172.5°W into two 7.5-degree ranges: One for GMT+12 and one for GMT–12. Obviously, when one is in the territorial waters of a nation, though, one should set clocks to local jurisdictional time instead. The "international date line," on the other hand, is simply a line drawn for convenience to show the "locations" of time transitions on the order of 24 hours. The line is itself not directly legislated by any governing body, nor does it have any meaning intrinsic to itself, except to distinguish where a roughly day-long disparity exists between adjoining "time zones" (whether nautical or jurisdictional). Regardless of their geographical location, nations can "move" this line so as to put themselves on one side or the other simply by making their own UTC offset positive or negative. As such, crossing into territorial waters could mean a clock shift of more than 24 hours; for instance, if one were to enter the UTC+14 portion of Kiribati from international waters which are geographically in the GMT–12 zone (ignoring, for now, the minor differences between the two timescales), one would shift clocks ahead by 26 hours. This is why the international date line is so jagged. Where appropriate, it is equivalent to the nautical date line on the 180th meridian. Elsewhere, it veers to either side to follow the appropriate boundaries of territorial waters, serving only to separate "date changes" (changes of about 24 hours) as a visual cue on a map to travellers. Since the boundaries of territorial waters are often hard to pin down precisely, different cartographers will tend to draw these boundaries on maps slightly differently, often with clean diagonal line segments to be aesthetically pleasing, as in http://upload.wikimedia.org/wikipedia/commons/6/61/International_Date_Line.p.... This does not mean these diagonal lines represent the actual geographical and logical boundaries where "date changes" occur; rather, the actual international date line is the result of the sum total of all the nearby nations' time zone legislation. Theoretically, there could even be geographical "pockets" where negative-offset nautical time is used, surrounded completely by positive-offset jurisdictional time (or, conversely, positive-offset nautical time surrounded by negative-offset jurisdictional time). Such a scenario would mean the international date line wouldn't actually be a line at all. (I do not know whether such a scenario actually exists at present, nor do I believe it would be an easy determination to find out.) Technically, a vessel travelling straight through such a region should have several "date changes" back and forth; however, a reasonable person travelling through such a region would probably just choose to "stay on one day or the other" as they found it convenient (keeping in mind the potential for disparity amongst others who may have made the inverse decision), until reaching a region where the date doesn't keep changing on them anymore. *;)* -- Tim Parenti