[tz] Extra transition for Europe/London with 2023d

[Paul Eggert]

On 2024-01-02 13:53, Brooks Harris via tz wrote:
> I suggest TzDb may want to have a look at this topic.  I think If these 
> improvements were made it would not alter the typical current behavior 
> of localtime(); the YMDhms representations and sequences would remain 
> the same. But the addition of these transitions are more complete and 
> honest to the underlying TzDb source data and this is important for some 
> types of extended functionality I'm pursuing.

It's never been a goal of zic to pack as much as possible information 
about the input into the TZif binary output file. Instead, the goal has 
been to optimize the output file size, as long as optimization doesn't 
change localtime's behavior. (Look for the word "optimize" in zic.c for 
more about this.)

It might be possible to add a flag to zic to tell it to output larger 
TZif files that contain transitions and other information that do not 
affect localtime but might aid other applications. However, I don't see 
how such a flag could preserve all the relevant information, without a 
change to the TZif file format. So unless we change the TZif format, 
users who want all the info in the .zi input files would need to look at 
the .zi files anyway.