[tz] EU Public Consultation summertime arrangements

Paul Eggert eggert at cs.ucla.edu
Thu Jul 12 23:55:37 UTC 2018

On 07/11/2018 03:28 PM, Michael H Deckers via tz wrote:
>    I do not think that the names of time scale are considered
>    to be EU business by anyone in the EU -- the EU follow the
>    principle of subsidiarity which defers decisions with local
>    scope to the locals. 

We could water down it to a suggestion that the EU bring the naming
problems to the attention of member countries and other interested
parties. Surely there would be no objection to that.

Also, I think it'd be helpful to suggest a solution to the problem. I'm
thinking that the name Central European Union Time (CEUT) would be a
good one if France, Germany and nearby countries adopt permanent UTC +02.

New version of proposed comment attached.

-------------- next part --------------
I am commenting as coordinator of the Time Zone Database (TZDB) hosted by the Internet Assigned Numbers Authority[1]. This database is used by most of the world’s cell phones and many of its computers to track time zones and summertime arrangements. The comments below have been circulated on the TZDB mailing list and attempt to reflect consensus there.

Although the simplest thing for computing applications would be to keep the EU rules unchanged, it would not be much of a problem to accommodate the abolition of twice-yearly clock changes in the EU, as has already been done in Russia and other countries. However, if such a change is done, the following technical points should be considered.

1. If timekeeping rules are changed, there should be at least a year’s notice before the changes take effect. Otherwise there is a good chance that some computer-based clocks will operate incorrectly after the change, due to delays in propagating updates to software and data. The shorter the notice, the more likely clock problems will arise. For more about this, please see “Changes to the tz database”[2] and “On the Timing of Time Zone Changes”[3].

2. If the EU rules are changed, the EU should record in a public document its member states’ related changes to civil time, so that interested parties can easily track European timekeeping changes. For best results, the document should also keep track of changes to civil time in EEA/EFTA countries, candidate countries, potential candidates, the Schengen area, and other countries not in the EU that decide to make a related change. This document would be purely informative, with no authority behind it.

3. If the EU abolishes twice-yearly clock changes, the resulting time zones should be considered standard time, not permanent summertime, to avoid conflicts with existing computer standards in widespread use. The notion of permanent summertime is not supported by the POSIX.1-2017 standard[4], which covers most of the computing servers in the European Union.

4. If the EU abolishes twice-yearly clock changes, there likely will be naming confusion when interested parties discuss the new timekeeping or use computer applications. One such application is the Unicode Common Locale Data Repository, which is related to TZDB and which records time zone abbreviations and names in many languages[5]. For example, if France and Germany decide to stay on UTC +02 all year, many English-language computer systems would likely call their new time zone “Eastern European Time (EET)” due to the long association between EET and UTC +02, even though neither country is in eastern Europe; conversely, some systems could well call the same UTC +02 timezone “Central European Time (CET)” even though that name has long been associated with UTC +01. Although the EU does not specify time zone names or their abbreviations, it would be helpful for it to bring this problem to the attention of member countries and other interested parties. Confusion might be lessened if new names were used for new timekeeping practices, e.g., if “Central European Union Time (CEUT)” was used for a new UTC +02 zone in France, Germany, and nearby countries.


[1] Time Zone Database, Internet Assigned Numbers Authority. 2018-05-01. <https://www.iana.org/time-zones>

[2] Changes to the tz database. 2018-05-01. <https://data.iana.org/time-zones/tz-link.html#changes>

[3] Johnson M. On the Timing of Time Zone Changes. 2016-04-23. <https://codeofmatt.com/2016/04/23/on-the-timing-of-time-zone-changes/>

[4] The Open Group Base Specifications Issue 7, 2018 edition, IEEE Std 1003.1-2017 (Revision of IEEE Std 1003.1-2008). See the variable “TZ” in section 8.3, “Other Environment Variables” <http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03>.

[5] By-Type Chart: Timezones:Europe. CLDR version 33. Unicode Consortium. 2018-03-09. <https://www.unicode.org/cldr/charts/33/by_type/timezones.europe.html>.

More information about the tz mailing list