UTC as basis for time legislation

Tobias Conradi tobias.conradi at gmail.com
Mon Sep 26 13:31:22 UTC 2011

On Mon, Sep 26, 2011 at 12:29 PM, Tony Finch <dot at dotat.at> wrote:
> Tobias Conradi <tobias.conradi at gmail.com> wrote:
>> I would assume that legal GMT in the UK in the year 2011 is exactly
>> the same as UTC. I could not find a law for that.
> No, the law here says legal time is GMT, but most official time signals
> are UTC. There have been a few unsuccessful attempts to deal with the
> mismatch between de jure and de facto UK time, e.g.
> http://www.publications.parliament.uk/pa/ld199798/ldhansrd/vo970611/text/70611-10.htm

So there is one flavor of GMT that is UTC and there is legal GMT which
is something different.

2011i/tzdata equates GMT for 2011 with UTC.

I would now reply to the former text:

On Sat, Sep 24, 2011 at 3:53 AM, Steve Allen <sla at ucolick.org> wrote:
> On 2011 Sep 23, at 18:44, <Paul_Koning at Dell.com> wrote:
>> So if country A says its legal time is an hour ahead of GMT and B says
>> they are an hour ahead of UTC, those are technically different statements.
>> However, to the approximation of tzdata, the outcome is the same:
>> both country A and B would be shown in the tzdata file as having an offset of 60 minutes.
>> Is that correct?
> It is correct under ITU-R TF.460-6.
To my understanding the statement of country A is ambiguous. Whether
there is approximation in tzdata depends on how one interprets the the
statement of country A. This has nothing to do with ITU-R TF.460-6.


Tobias Conradi
Rheinsberger Str. 18
10115 Berlin


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