[tz] Proposal: validation text file with releases

[Paul Eggert]

Stephen Colebourne wrote:
> I think what Jon is asking, and I'm confirming, is that this data
> *should*  be considered part of the public data exposed by the tzdb
> project.

When I wrote that data, I didn't worry about the DST-vs-STD offset.  I cared 
only about the correctness of the sum of the offset and standard time, because I 
knew that only the sum mattered.  At this point it would be a nontrivial project 
to verify that these offsets actually make sense everywhere in tzdata.  (They 
usually do, but in some cases I vaguely recall that there were issues.)  Until 
such a project is done (and I'm not volunteering :-) it would be misleading to 
document that the offsets are meaningful.

There are many ways in which tzdata source code can differ in appearance while 
meaning the same thing.  For example, although a time can be written "1:00" or 
"01:00" or "1:00:00" or "+1:00", none of this matters in zic output.  This sort 
of thing is intended to be obvious, but unfortunately it was not obvious in this 
case.