[tz] "non-standard" timezones

Robert Elz kre at munnari.OZ.AU
Mon Jan 7 10:22:57 UTC 2013

    Date:        Sun, 6 Jan 2013 18:29:04 +0000
    From:        Shawn Steele <Shawn.Steele at microsoft.com>
    Message-ID:  <a1041674394d4a9f98ddb57f08a6e382 at BN1PR03MB040.namprd03.prod.outlook.com>

  | but are there *any* known cases where people make exceptions to
  | the standard?

That depends, I guess, on what it would take to qualify as a case that
counts for your purposes.

I have certainly created new timezones when I have been testing stuff,
kind of "what if" cases for the timezone database, and/or for making sure
that my understanding of how things work matches reality.

But none of those zones ever get used for anything "real", no ordinary
application would ever see them, and I certainly have no need for any
standardised kind of name for them (TZ=$PWD/test1 (or something) works
just fine)

In general, we attempt to cover all timezones that anyone could ever
want - as we attempt to make sure the database contains everything that
exists (for many people, far more than they claim to need, as many
people, at least claim, not to care about historical differences).
That makes it rare for anyone to need to create a new real zone - if
it is important enough for someone to need to do that, then it probably
qualifies to be included in the tz database.

  | Even if they're reusing names?

Reusing names would just be altering the definition of a zone, which, other
than to update it, or correct an error, doesn't seem like a particularly
useful thing to do (we have no shortage of file names, creating a new one
is not a difficult task...)

  | (Reusing names for different behavior seems bad for interop).

There isn't really any interop issue, at least, not for the names as
they're defined and used here, they're purely a system local identifier
that selects a particular timezone - we don't expect them to be passed
around (other groups define timezones that are used for interoperability
purposes, like shared calendars, and I think have different naming
schemes, as much as names are needed at all.)


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