Timezone translations

Mark Davis mark.davis at jtcsv.com
Sat Jun 4 16:41:42 UTC 2005

Thanks for the information. If you could file a bug at
http://www.jtcsv.com/cgibin/locale-bugs?user=guest, we'd appreciate it.

Ideally we need 6 names, starting with 3 full ones:

generic: British Time
winter: ?
summer: British Summer Time

All of the names have to uniquely map to a tzid to support roundtripping.
That is, given a locale, if someone formats a date + tzid and then parses
the result, he or she gets back exactly the same date and tzid.

Thus we can't use the long name Greenwich Mean Time or the abbreviation GMT
to refer to the "British Winter Time", because GMT (= Etc/GMT) is invariant
(no daylight/summer time rules). We can, however, use a qualifier, like
"Greenwich Mean Time (UK)" or "GMT (UK)".

We also need three distinct abbreviations (if available).

generic: BT
winter: ?
summer: BST?

If an abbreviation is not specified, the fallback will be the corresponding
long name. If a long name is not specified, the fallback is to a country
name (if a single zone) or country-city name combination.

Another twist. The timezone files that are generated are for the default
language values, in this case, English. The values can actually vary by
individual country. So we have to decide whether these changes should be
made for all of English, or for just, say, the UK and Ireland (en_GB,
en_IE). I don't see any reason for not doing it for all of English ("Summer
Time" is a more meaningful term than "Daylight Savings Time" anyway), but if
there are any reasons not to do that you might mention them.

And including the rest of the sources you cite in the bug report would be
very helpful.


----- Original Message ----- 
From: "Peter Ilieve" <peter at aldie.co.uk>
To: <tz at lecserver.nci.nih.gov>
Sent: Saturday, June 04, 2005 04:32
Subject: Re: Timezone translations

> On 4 Jun 2005, at 01:56, Mark Davis wrote:
> > BTW, I regenerated the timezone localizations, based on the latest
> > CLDR 1.3
> > data. See
> >
> > http://www.unicode.org/cldr//data/dropbox/timezones/
> >
> > We are still not complete, but are making progress.
> Unfortunately, some of the progress is in the wrong direction. :-)
> The en_timezones.html file contains this for the UK (Europe/London):
> ---
> 348  United Kingdom  Europe/London  GB-Eire; GB
>           generic             standard                 daylight
> gmt      GMT-00:00/-01:00    GMT-00:00                GMT-01:00
> short    BT                  BST                      BDT
> long     British Time        British Standard Time    British
> Daylight Time
> ---
> The short and long rows are completely wrong. We don't use the name
> British Daylight Time or the abbreviation BDT for our daylight saving
> time (and we don't use the term daylight saving either). We call
> the concept summer time, named British Summer Time, with abbreviation
> BST. We use Greenwich Mean Time as the name for our standard time,
> abbreviated as GMT. We did use the name British Standard Time for
> an ill-fated experiment between 1968 and 1972 where we had the
> clocks an hour in advance of GMT all year round. This name was
> no doubt chosen so the same BST abbreviation could be used for
> what was in effect summer time all year.
> The BST abbreviation for standard time is the biggest problem
> as it gives the wrong meaning for an abbreviation in common use,
> which will only cause confustion.
> I've never heard the name British Time used for `generic' time,
> whatever that might be; and if you mention BT to the average UK
> person they will think of our phone company: British Telecommunications.
> Some URLs to back this up:
> <http://www.dti.gov.uk/er/bankhol.htm> A UK government site with
> bank holiday dates, and Timetable for British Summer Time link near
> the bottom.
> <http://www.nmm.ac.uk/server/show/nav.00500300f00h> A National Maritime
> Museum (home of the Greenwich Observatory) page with a bit about
> summer time near the bottom, showing use of GMT and BST.
> <http://www.publications.parliament.uk/pa/ld199798/ldhansrd/vo970611/
> text/70611-10.htm#70611-10_head0>
> The second reading debate on a Bill introduced by Lord Tanlaw which
> would have made UTC the UK's legal time. The second paragraph of column
> 965 gives the basis for GMT as the UK's legal time. The Bill failed.
> And of course, <http://www.srcf.ucam.org/~jsm28/british-time/>,
> Joseph Myers' page with all the gory UK legal detail.
> I noticed the BDT abbreviation in the OS X 10.4 (Tiger) Mail program
> and submitted a bug report to Apple (4078227). I guess they got
> it from this CLDR data.
> Where did these names and abbreviations come from? How can they get
> fixed?
>          Peter Ilieve        peter at aldie.co.uk

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