Tobias Conradi said:
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/706...
So there is one flavor of GMT that is UTC and there is legal GMT which is something different.
Yes and no. Legal time in the UK is Greenwich mean time (or that plus one hour). That means mean solar time at Greenwich, which is equal to UT1 within a few milliseconds (it depends on exactly what you mean by "mean" and exactly where "Greenwich" is). The easiest-to-find sources of time in the UK are all UTC. To actually get your hands on GMT you need a source of DUT and to do the subtraction. That does *not* mean that "there is one flavor of GMT that is UTC". I've not found a reported law case where the difference is explored, let alone where it mattered. The closest I got was a case hinging on a time difference of 8 seconds between two events, but there was no mention of which of GMT or UTC applied.
2011i/tzdata equates GMT for 2011 with UTC.
In effect, yes. It takes the view that the difference is too small to matter *in this context*.
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.
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.
No. The statement of country A is *not* ambigous (except at the millisecond level as mentioned above). The statements are technically and de jure different. Whether country A actually meant UTC when it wrote GMT is a separate question that you'd have to ask country A.
This has nothing to do with ITU-R TF.460-6.
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